The head of the UN sanctions committee for Angola says that the embargo on the Unita rebels' diamond and arms trade is having an effect.

Canadian diplomat Robert Fowler said he was convinced that Unita's ability to wage war finally appeared to be decreasing.

Mr Fowler was visiting Angola with a team of experts to examine how to better enforce a 1993 arms and fuel embargo and a 1998 ban on the rebels' diamond exports.

He said the government forces' recent success in regaining diamond-mining areas had helped deprive Unita of funding.

"I hope the recent military victories and a tighter application of sanctions hasten the end of the war," he said.

Unita's profit from diamond sales was estimated to be as high as $4bn in the past eight years.

Although Mr Fowler was unable to provide figures, he said the rebels' trade in diamonds had already slipped.

Arms cache

Mr Fowler met President Jose Eduardo dos Santos, senior cabinet members and the government's top military commander, General Joao de Matos.

He also talked to former rebels who had defected or been captured by government forces.

Mr Fowler visited the rebels' former central highland stronghold of Andulo, which the army captured three months ago, where he examined a Unita arms cache.

He sought to expose the countries and individuals supplying the weapons in breach of UN sanctions.

He told the BBC's correspondent in Luanda, Lara Pawson, that 98% of the weapons appeared to have come from Eastern Europe.

"I can't be more specific," he said.

"There may be experts who can tell the difference between a Ukrainian BMP2 and a Russian BMP2 and a Bulgarian BMP2, but I can't."

Unita - the National Union for the Total Independence of Angola - resumed battles with the government in December 1998, confirming long-held suspicions that the sanctions were not working.

Mr Fowler will report to the UN Security Council on Tuesday, and present a full report by March.