BY PABLO BACHELET

Colombia's attorney general arrived in Washington Tuesday in an effort to ease growing concerns in the Bush administration that the country is not doing enough to curtail human rights abuses, risking the loss of up to $65 million in military aid.

The Bush administration has generally lauded Colombian President Alvaro Uribe's achievements in security and counternarcotics, citing a broad array of data, from declining kidnapping rates to a drop in coca plantations.

Colombia dispatched its attorney general, Luis Camilo Osorio, to brief State Department officials Tuesday and U.S. Attorney General John Ashcroft today as top administration officials hardened their language on alleged human rights abuses in Colombia.

Osorio's visit came as Colombian prosecutors charged three soldiers with the killing of three leftist labor union activists, a sign that members of the armed forces will be punished if they break the law, Carolina Sánchez, a spokeswoman for Osorio, said in a phone interview from Bogotá.

The United States has disbursed more than $3 billion to the country since 2000 in an effort to cut drug production and weaken narcotics-funded illegal armed groups.

Last week Secretary of State Colin Powell urged Uribe to ``keep his eye on human rights and civil rights, to make sure that while he is cracking down, it is done in a way consistent with acceptable human rights standards.''

A negative certification to Congress of Colombia's human rights record could stop the disbursement of up to $65 million of this year's $259 million military aid package for Colombia, according to State Department officials.

Colombia must show ''substantial progress'' on issues that range from suspending members of the security forces accused of rights violations to ''vigorously prosecuting'' members of the armed forces accused of abusing human rights or working with the paramilitaries, according to a State Department official who declined to be identified.

He said the United States, though heartened by achievements in security and counternarcotics, was ``troubled by the persistent problem of impunity.''

''Despite some prosecutions and convictions, the authorities rarely brought high-ranking officers of the security forces charged with human rights offenses to trial,'' the official added.

Osorio presented a detailed report on Colombia's advances on human rights ''with an eye on the certification,'' Sánchez said.