The UN secretary general's special representative on human rights has criticised the Thai Government for its handling of a major initiative against alleged drug dealers.
By the BBC's Dan Griffiths
Speaking at the end of a week-long tour in Thailand, Hina Jilani said the authorities had used the campaign to target minority groups in the country.
The government's so-called war on drugs was a three month law enforcement campaign beginning in March, designed to rid the country of its image as a haven for drug dealers.
More than 2,000 people died in Thailand's anti-drugs campaign
Prime Minister Thaksin Shinawatra declared it a major success - but not everyone agrees.
Human rights groups have criticised what they call the violent conduct of the campaign - and say that more than 2,000 people have been killed by police since March.
Kofi Annan's representative on human rights, Hina Jilani, is the latest to add her voice to that criticism.
"There are indications that this campaign against drugs is being used by security forces to target the more marginalised communities," she said.
She added that those communities had been placed at risk as a result of the campaign.
Mr Thaksin has consistently denied this criticism.
He says the initiative has broad support across the nation - and there is no doubt that many ordinary Thais are happy that he has taken a stand on one of the country's most entrenched problems.
In fact, it has been such a political success that Mr Thaksin is expected to launch a new campaign at the end of the month - this time against criminal gangs.