The head of the UN anti-drug agency says Afghanistan needs to do much more to fight the sharp rise in heroin production of the past few years.

Antonio Maria Costa praised efforts the government had made to control drugs, but said that opium poppies were still grown in large parts of the country.

He was speaking after talks in Pakistan with President Pervez Musharraf.

Mr Costa warned the president of the risk of an increase in trafficking of Afghan heroin into Pakistan.

He said that the Afghan government was moving in the "right direction" to tackle the drugs trade, but needed to do more, particularly in its poppy crop eradication programmes.

Last year Afghanistan produced more than 4,000 tons of illegal opium, estimated to be 87% of world production.

"I expect some reduction (this year)," Mr Costa told the Associated Press in an interview at the end of a three-day visit to Pakistan. "I don't know whether it's going to be significant... We just don't know yet."

He said that Afghan drugs smuggling risked undermining Islamabad's efforts to eradicate its own drug trade.

The Afghan President, Hamid Karzai, said after aid talks in Brussels that he hoped there would be a reduction of some 30% in opium production this year.