Colombian President Alvaro Uribe has fired at least two dozen army officers, including three generals, following an investigation into suspected executions initially reported as combat deaths.

President Alvaro Uribe made the announcement Wednesday, saying the probe found that members of the armed forces could have been involved in killings. The Colombian leader also said any violations of human rights cannot be allowed.

The comments followed public outcry over the deaths of 19 young men who disappeared several weeks ago from a poor Bogota suburb. Their remains were discovered recently in mass graves in the country's northeast. The civilians were originally declared to be rebels killed during fighting.

A day earlier, the human rights group, Amnesty International, urged the United States and other nations to suspend military aid to Colombia until Colombia can guarantee its security forces are not engaged in civilian killings.

The developments also come as the United Nations High Commissioner for Human Rights, Navi Pillay, visits Colombia for the first time since assuming her post last month.

The U.N. says Pillay will be in Colombia for one week to review the situation there. She is expected to meet with President Uribe and other politicians, members of the judiciary and civil society, and U.N. colleagues to discuss human rights concerns.

Colombia is mired in a long-running civil war that involves government forces, leftist rebels and rightist paramilitary forces. The violence has claimed the lives of more than 200,000 people.

Some information for this report was provided by AFP, AP and Reuters.