* Kerry makes show of unity with Karzai
* U.S. transfers responsibility for prisoners (Adds Karzai, Kerry quotes at news conference)
By Arshad Mohammed
KABUL, March 25 (Reuters) - U.S. Secretary of State John Kerry made a show of unity with Afghan President Hamid Karzai during a short visit to Afghanistan on Monday, following weeks of heightened tensions between the two countries.
Kerry made the unannounced visit to Afghanistan in order to discuss a host of issues including attempts to stabilise the country before most foreign troops leave by the end of 2014, the transfer of security responsibility to Afghan forces and Afghanistan's elections, a U.S. official told reporters.
After a private meeting, the two held a news conference at the presidential palace in Kabul. During it Karzai confronted questions about his remarks earlier this month in which he accused the Taliban of undertaking attacks "in service of America".
Numerous press reports stated he was suggesting the U.S. and the Taliban were colluding, but he rejected that interpretation at the news conference.
"I never used the word 'collusion' between the Taliban and the U.S. Those were not my words. Those were the (words) picked up by the media," he said.
Kerry also referred to the comments. "I am confident that the president absolutely does not believe that the United States has any interest except to see the Taliban come to the table to make peace."
Kerry, making his first visit to Afghanistan as secretary of state, also acknowledged America's hand-over earlier in the day of control of Afghanistan's largest detention facility, adjacent to the Bagram military base north of Kabul.
Control of the detention facility and the prisoners inside was formally ceded to the Afghans during a ceremony on Monday morning, ending a longstanding bone of contention between the two countries.
Transfer of control of the prison had been repeatedly delayed over the past year, in part due to U.S. concerns that inmates dangerous to coalition forces might be released.
"As of today, we don't have prisoners (in Afghanistan). Whatever is occurring here is under the control of the Afghan people," Kerry said.
Despite that assertion, earlier in the day the Afghan commander of the Bagram detention facility, Gulam Farooq Barakzai, said a very limited number of detainees remained in U.S. custody and were expected to be handed over to the Afghans by the "end of next week".
Asked for details on how the prisoner transfer agreement would work, Karzai said the U.S. had agreed to share intelligence about what it viewed as highly dangerous prisoners and would be consulted before any eventual release.
Karzai said an Afghan review board would examine intelligence and decide whether detainees should be released, before a final exchange of views between the U.S. military commander and the Afghan defence minister.
Karzai is due to travel to Qatar within days to discuss the peace process and the opening of a (Taliban) office for conducting negotiations. The trip comes after years of stalled discussions with the United States, Pakistan and the Taliban.
Commenting on Karzai's trip, the U.S. official told reporters: "I wouldn't want to overplay it but I think that it's a very positive sign. It's another step on a continued path toward... getting to some sort of reconciliation process.
"Nobody is expecting that he will open an office there in a week. Nobody is expecting that he will be sitting down with Taliban in a week. This is a long process and this is one more small but positive step in that ... process."
The official said Kerry had wanted to visit Pakistan on this trip but had decided not to given the May 11 election, in part to avoid any appearance of seeking to influence what would be Pakistan's first civilian-to-civilian electoral handover.
"We wanted to be, you know, holier than the Pope on this one, on staying away while the electoral process unfolded," said the U.S. official. (Additional reporting by David Alexander and Dylan Welch; Editing by Nick Macfie and Stephen Powell)