WASHINGTON -- Despite intensified eradication, coca production in Colombia increased by about 25 percent last year, the Bush administration said, contradicting Colombian government claims of a significant decline.

In releasing the figures Thursday, the White House Office of National Drug Control Policy admitted that the results of the escalating effort were less than it had hoped for.

The gloomy assessment contrasted sharply with the announcement last week by Colombian Justice Minister Romulo Gonzalez that his figures showed a decline in coca production by about 16 percent -- from 392,000 acres to 336,000 acres -- between August 2000 and December 2001.

He said that trend was a "clear demonstration" the U.S.-backed eradication campaign was working.

The White House statement attributed part of its finding of an increase to the inclusion of a coca growing area not surveyed in 2000 because of cloud cover.

It also said some of the coca included in the estimate was later eradicated by spray planes.

Based on satellite imagery, the coca crop was reported to be 417,430 acres last year, 82,992 more than in 2000, the statement said. Last week, the State Department said nearly twice as many acres were sprayed last year compared with 2000.

Implications for U.S.

Colombia's huge coca crop has serious implications both for that country and for the United States.

Earnings from coca -- the raw material for cocaine -- support insurgencies of the left and the right in Colombia that have devastated the country for years.

And cocaine addicts in the United States rely almost exclusively on imports from Colombia to maintain their habit, Colombia serving as the largest producer and distributor of coca in the world.

The White House statement said the figures "underscore the pervasiveness of cultivation and trafficking in Colombia; the magnitude and complexity of Colombia's interlocking security, drug control, and economic challenges; and the need for sustained U.S. engagement."

It said the security environment in Colombian drug cultivation regions has made it difficult to implement counterdrug programs.

"We will continue to work with the government of Colombia to achieve our mutual objectives of strengthening democracy, eliminating drug trafficking, and enforcing the rule of law," the statement added.

Part of the increase occurred in a huge zone that President Andres Pastrana ceded to leftist FARC guerrillas in 1998 in hopes of spurring peace talks.

Pastrana called off the initiative two weeks ago, complaining that the rebels, instead of using the Switzerland-sized area to promote peace, were using it for military purposes and for the coca trade.

The Clinton administration undertook a major commitment to curb illicit narcotics flows from Colombia in 2000. Congress approved $1.3 billion in assistance, mostly for helicopters destined for Colombia's military.

Officials cautioned at the time that the process would take time but the White House statement suggested that progress has been slower than expected.