By ANDREW SELSKY, Associated Press Writer

BOGOTA, Colombia (AP) - President Alvaro Uribe vowed on Friday to press ahead with U.S.-financed fumigation of cocaine-producing crops, even as a new White House report found that a massive aerial spraying offensive last year failed to dent the area of coca under cultivation in Colombia.

Critics of Washington's effort to crush drug production in Colombia - the world's main cocaine-producing country and a major supplier of heroin - say the report indicates the Colombian and U.S. governments are losing the war on drugs, which has cost more than $3 billion in U.S. aid here since 2000.

``The U.S. government's own data provides stark evidence that the drug war is failing to achieve its most basic objectives,'' said John Walsh, of the Washington Office on Latin America, a think tank critical of U.S. drug policies in Colombia.

The report by the White House Office of National Drug Control Policy said that despite a record-setting aerial eradication offensive, 281,694 acres of coca remained in Colombia at the end of 2004 - slightly more than the 281,323 acres that were left over in 2003 after spraying.

Walsh also pointed out that prices of cocaine and heroin have been steadily dropping over the years on U.S. streets, indicating availability of the drugs has not diminished.

Peasant farmers grow most of the coca - the bushy green plant that provides the main ingredient of cocaine - in Colombia, convert it to coca paste and sell it to Colombian rebels, paramilitaries or other groups that traffic in drugs, who purify it into cocaine and export it.

Adam Isacson, a Colombia expert with the Center for International Policy in Washington, said the White House report released on Good Friday demonstrates that the peasants - most of whom live in poverty and who have few alternate means of employment - are constantly replanting coca after their crops are sprayed by the crop dusters.

``The inescapable conclusion we can draw from this data is that our fumigation program is not discouraging Colombian peasants from growing coca,'' Isacson said.

The Associated Press reported last month that large-scale coca production was moving for the first time into the extensive jungles of Choco state, in northwest Colombia, with peasant farmers felling chunks of virgin rainforest in order to plant millions of coca seedlings.

Uribe, in an interview with local RCN radio, said he was undeterred by the report by the White House drug office.

``Our will is to continue seizing the drugs and to continue with the fumigation,'' Uribe said.

Last year, 337,427 acres of coca were fumigated, the White House report said.

Uribe added that he was waiting for the United Nations to release its own report on coca production in coming months.

Sometimes the reports, using different systems to estimate the area under cultivation, contradict each other. For example, the U.N. drug agency said that in 2003, 212,506 acres were used to grow coca in Colombia, while the White House drug office's estimate was 281,323 acres.

The White House drug office said that while the area under coca cultivation remained ``statistically unchanged'' over the previous year, the fumigation diminished the potential production of cocaine by 7 percent in 2004 to 430 metric tons, because newly planted fields produce less cocaine than mature coca.