Twitter has apologised after an investigation found its ad-targeting tool accepts keywords words like 'anorexia' and 'bulimia' for reaching vulnerable teenagers.

The social media website has issued an apology over allowing adverts on the social media website which target vulnerable users.

An investigation by the BBC found it was possible for advertisers to target vulnerable groups by using keywords "anorexic", "bulimic", "anorexia" and "bulimia".

The firm allows advertisers to target people using specific keywords based on what they share in tweets, like, or what they search.

The BBC ran an advert to an audience of 13 to 24-year-olds using the keywords "anorexic", "bulimic", "anorexia" and "bulimia".

Twitter estimated the target audience amounted to 20,000 people. The post was seen by 255 users, and 14 people clicked on the link before we stopped it.

Mental health support

Bipolar disorder -  bipolaruk.org, hearing-voices.org, intervoiceonline.org, nice.org.uk, rethink.org, sane.org.uk

Body dysmorphic disorder (BDD) -  bipolaruk.org, hearing-voices.org, intervoiceonline.org, nice.org.uk, rethink.org, sane.org.uk

Borderline personality disorder (BPD) -  bipolaruk.org, hearing-voices.org, intervoiceonline.org, nice.org.uk, rethink.org, sane.org.uk

Dissociation and dissociative disorders - Clinic for Dissociative Studies clinicfordissociativestudies.com, Epilepsy Action epilepsy.org.uk, European Society for Trauma and Dissociation estd.org, First Person Plural firstpersonplural.org.uk, The International Society for the Study of Trauma and Dissociation (ISSTD) isst-d.org, Non-Epileptic Attack Disorder (NEAD) nonepilepticattackdisorder.org.uk, National Society for the Prevention of Cruelty to Children (NSPCC) nspcc.org.uk, Positive Outcomes for Dissociative Survivors (PODS) pods-online.org.uk, Survivors UK survivorsuk.org, The Survivors Trust thesurvivorstrust.org

Eating disorders - You can also talk in confidence to an adviser from eating disorders charity Beat by calling their adult helpline on 0808 801 0677 or youth helpline on 0808 801 0711.

Hoarding - British Psychological Society (BPS) bps.org.uk, Rainbow Red rainbowred.co.uk, 0845 390 6232 ocdaction.org.uk, ocduk.org, thesilverline.org.uk, hoardingdisordersuk.org, helpforhoarders.co.uk

Hypomania and mania - Be Mindful bemindful.co.uk, Bipolar UK bipolaruk.org.uk , British Association for Behavioural and Cognitive Psychotherapies (BABCP) babcp.com, British Association for Counselling and Psychotherapy (BACP) 01455 883 300 itsgoodtotalk.org.uk, hearing-voices.org, intervoiceonline.org, nice.org.uk, rethink.org, sane.org.uk

Obsessive-compulsive disorder (OCD) - 0845 390 6232 ocdaction.org.uk, ocduk.org

Paranoia  - therapeuticcommunities.org, talktofrank.com, napac.org.uk, nice.org.uk

Postnatal depression & perinatal mental health - Action Postpartum Psychosis (APP) app-network.org, The Association for Post Natal Illness apni.org, Birth trauma association birthtraumaassociation.org.uk, The Breastfeeding Network 0300 100 0212 breastfeedingnetwork.org.uk, Elefriends elefriends.org.uk, Family Action family-action.org.uk, Family Lives familylives.org.uk, fatherhoodinstitute.org, home-start.org.uk The Lullaby Trust lullabytrust.org.uk, Maternal OCD maternalocd.org, The Miscarriage Association miscarriageassociation.org.uk, NCT nct.org.uk, Sands sands.org.uk, Start4Life nhs.uk/start4life and Tommy's tommys.org

Post-traumatic stress disorder (PTSD) - Anxiety UK anxietyuk.org.uk, ASSIST trauma care assisttraumacare.org.uk, Birth Trauma birthtraumaassociation.org.uk, Combat Stress combatstress.org.uk, Disaster Action disasteraction.org.uk, EMDR UK & Ireland emdrassociation.org.uk/, Elefriends elefriends.org.uk, Freedom From Torture freedomfromtorture.org, Lifecentre lifecentre.uk.com, Moodjuice moodjuice.scot.nhs.uk, PTSD resolution ptsdresolution.org, Survivors Trust thesurvivorstrust.org

Premenstrual dysphoric disorder (PMDD) - British Association for Counselling and Psychotherapy (BACP) bacp.co.uk, IAPT iapt.nhs.uk/services, International Association for Premenstrual Disorders iapmd.org and National Association for Premenstrual Syndrome (NAPS) pms.org.uk

Psychosis - bipolaruk.org, hearing-voices.org, intervoiceonline.org, nice.org.uk, rethink.org, sane.org.uk

Schizoaffective disorder - babcp.com, bacp.co.uk, hearing-voices.org, intervoiceonline.org, sane.org.uk

Schizophrenia - elefriends.org.uk, hearing-voices.org, nationalparanoianetwork.org, rcpsych.ac.uk

Seasonal affective disorder (SAD) - CALM (Campaign Against Living Miserably) 0800 58 58 58, info@depressionuk.org, depressionuk.org, nice.org.uk, rethink.org, sane.org.uk

Tardive dyskinesia - tremor.org.uk, dystonia.org.uk, hearing-voices.org, mhra.gov.uk, parkinsons.org.uk NHS Direct 0845 46 47

An investigation by the BBC also found discriminatory terms such as "transphobic", "white supremacists" and "anti-gay" were not being excluded during the ad setup process.

"Neo-Nazi", which also slipped through the net, could reach an estimated audience of between 67,000 and 81,000 people in the UK, the report claims.

Meanwhile, 92,900 to 114,000 accounts were predicted for the keywords "islamophobes", "islamaphobia", "islamophobic" and "#islamophobic".

Despite Twitter's website saying adverts can be reviewed before running in campaigns, it is claimed generic test adverts using offensive terms were approved.

"They are submitted for approval on an automatic basis, based on an account's advertising status, its historical use of Twitter and other evolving factors," it states.

Twitter responded saying it does ban certain sensitive words from its ad tool but the particular examples were an "error" and it has now fixed the issue.

Eating disorders - how to get help

How do I get help?

If you think you may have an eating disorder, even if you aren't sure, see your GP as soon as you can.

They'll ask you questions about your eating habits and how you're feeling, and will check your overall health and weight.

If they think you may have an eating disorder, they should refer you to an eating disorder specialist or team of specialists.

It can be very hard to admit you have a problem and ask for help. It may make things easier if you bring a friend or loved one with you to your appointment.

You can also talk in confidence to an adviser from eating disorders charity Beat by calling their adult helpline on 0808 801 0677 or youth helpline on 0808 801 0711.

"Twitter has specific policies related to keyword targeting, which exist to protect the public conversation," a spokeswoman said.

"Preventative measures include banning certain sensitive or discriminatory terms, which we update on a continuous basis.

"In this instance, some of these terms were permitted for targeting purposes. This was an error.

"We're very sorry this happened and soon as we were made aware of the issue we rectified it.

"We continue to enforce our ads policies, including restricting the promotion of content in a wide range of areas, including inappropriate content targeting minors."

Video Loading

The eating disorder charity Anorexia and Bulimia Care's chairman Daniel Magson said: "I've been talking about my eating disorder on social media for a few years now and been targeted many times with adverts based on dietary supplements, weight loss supplements, spinal corrective surgery.

"It's quite triggering for me, and I'm campaigning to get it stopped through Parliament. So, it's great news that Twitter has now acted."