by Kylie Morris BBC, Bangkok

Announcing the results of an internal investigation, the police boss reduced by half the number of people thought to have died as a result of the first three months of the campaign.

The Thai police chief has rejected criticism from rights groups

He says only 1,329 Thais died over drugs, arguing that the other 1,300 killings had nothing to do with the illegal trade.

Presenting a confusing array of figures to the gathered media, General Sant Sarutanond insisted his police had done the right thing in the so-called "war on drugs".

He accepted that the total number of people who died when the campaign first began was higher than average, but said that at that time, orders were given and there was a mandate from the Thai people for an all-out war, which the police were supposed to win.

He added that the same outcome would not have been possible without anyone dying.

Thailand's top policemen rejected criticism from international and local rights groups, saying that was their job.

He said at a government to government level, the Thai approach was well understood.

Even before the police investigation had been completed, Thailand's National Human Rights Commission expressed its concern that the police should not be responsible for investigating their own behaviour.

The inquiry, which took less than two weeks, followed comments by Thailand's revered king, suggesting that the government should clarify the high number of deaths.

Police General Sant said that based on the inquiry, 72 people died as a result of extra-judicial killings.

But he added that did not necessarily mean they were killed by the police.

The government has long held that the apparently high number of murders resulted from "silencings" - that is, killings ordered by drug bosses to keep themselves beyond the reach of the law.