The United States has decided to waive drug sanctions against Colombia on national-security grounds, senior administration officials said.

Secretary of State Madeleine Albright has approved the waiver, which is expected to be signed by President Clinton, the officials said. But they cautioned that Clinton in the past had altered such recommendations at the final stage.Mexico will also be certified again this year as cooperating fully in the war against drugs, the officials said, because of improved counter-narcotics efforts over the last year.

The administration's decision last year to certify its close ally Mexico in the face of evidence of political corruption by drug traffickers there provoked congressional protests that the administration was strong in speaking out against drugs but weak in action.

The decision to waive sanctions on Colombia, which was fully decertified last year and the year before without a waiver, is bound to be controversial. The decision is based on the progress made against the Cali cartel and other drug traffickers by Gen. Rosso Jose Serrano, who is praised by key House Republicans for turning a corrupt Colombian police force into a more efficient and professional one.

Furthermore, the officials said, the term of President Ernesto Samper of Colombia, who is accused by Washington of accepting $6 million in campaign contributions from drug traffickers in 1994, ends in August, and he cannot be re-elected.

Colombia is also facing increased consolidation of the cocaine cartels on its territory because of a drop in Peruvian production, the officials said, making it more important that Washington work with the Colombian government and not isolate or alienate it. In addition, the officials said, guerrillas trying to overthrow the government are obtaining increased aid from drug cartels.

Those countries not certified can lose U.S. foreign aid and support for development bank loans unless President Clinton grants them a waiver for national-security reasons.

Latin American countries generally regard certification as an exercise in Yankee arrogance, given that Americans are choosing to buy the drugs that Latin Americans grow. They suggest that Washington do more to reduce domestic demand.

Officials said that Colombia still provided the largest amount of cocaine entering the United States, but, one said, "we believe Colombia has made progress, especially in destroying crops, even if not enough to fully certify them."