KABUL, Afghanistan - U.S. troops and their Afghan allies killed 12 insurgents in fighting near the Afghan border with Pakistan and arrested 15 suspected drug traffickers in a separate operation to the south.

The United Nations called for Afghan human rights investigators to be allowed into Bagram, the main U.S. base in Afghanistan, after the New York Times reported that poorly trained U.S. soldiers there had repeatedly abused prisoners.

Afghan President Hamid Karzai, on the eve of his Monday meeting with President Bush in Washington, said he was angry about the reported abuse and called for more Afghan control over the operations of the 16,700 U.S. troops in his country as well as punishment for any U.S. soldiers who mistreat prisoners.

Also on Sunday, an Afghan government spokesman said a kidnapped Italian aid worker Clementina Cantoni is alive and healthy and that Afghan officials are in contact with her kidnappers. The announcement came two days after reports quoting the purported kidnapper as saying he had killed her because the government hadn't agreed to his demands.

Saturday's fighting in eastern Paktika province left one U.S. soldier slightly wounded. Spokesman Lt. Col. Jerry O'Hara said rebels had sneaked across the border from Pakistan and opened fire on American and Afghan forces.

After a winter lull, loyalists of the ousted Taliban regime and other militants opposed to Karzai's U.S.-backed government have ramped up their insurgency.

Fifteen suspected drug traffickers were arrested and a large quantity of opium seized in a major counter-narcotics swoop in southern Afghanistan, local officials said.

The latest violence came as Karzai prepared to meet Bush in Washington, where the two leaders are expected to discuss the prisoner abuse allegations among other topics.

The New York Times on Sunday detailed fresh allegations of mistreatment of prisoners by U.S. forces, citing the Army's criminal investigation into the deaths of two Afghans at the Bagram base north of the capital Kabul in December 2002.

Karzai - often viewed by critics as an American puppet - insisted that abusers be punished.

"This is simply not acceptable," he told CNN. "We are angry about this. We want justice. We want the people responsible for this sort of brutal behavior punished and tried and made public."

The U.S. military has said it would not tolerate any abuse. The White House said Friday that Bush was "alarmed" by the reports of abuse and wants them investigated thoroughly. The White House said seven people were being investigated in connection with abuse at Bagram.