* U.S. transfers responsibility for Afghan prisoners
* Karzai says peace talks without Pakistan won't succeed (Adds Kerry, Karzai quotes, paragraphs 6, 10, 19)
By Arshad Mohammed
KABUL, March 25 (Reuters) - U.S. Secretary of State John Kerry and Afghan President Hamid Karzai made a show of unity on Monday after weeks of heightened tensions over prisoner transfers and Afghan suggestions of U.S.-Taliban collusion.
Kerry made a brief, unannounced visit to Afghanistan 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 2014 elections, a U.S. official told reporters.
After a private meeting that lasted several hours, the two held a news conference where 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 held in the presidential palace in Kabul.
"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 said the two men had discussed the matter but he played it down. "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."
Making his first visit to Afghanistan as secretary of state, Kerry 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 U.S.-Afghan bone of contention.
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. Whatever is occurring here is under the control of the Afghan people," Kerry said. An aide said he was referring only to Afghan citizens.
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 United States 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 board would review 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.
U.S. WELCOMES KARZAI TRIP TO QATAR
The Afghan president 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 talks with the United States, Pakistan and the Taliban.
U.S. officials called his trip a step in the right direction
"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," said one official.
Kerry repeated the U.S. call for the Taliban to enter into talks and a wider political process and issued a veiled threat if they did not, saying U.S. President Barack Obama had yet to say how many U.S. troops will remain in the country after 2014.
Karzai stressed the need to bring neighbouring Pakistan into such a negotiation. U.S. and Afghan officials have long said the Taliban forces enjoy sanctuary across the border in Pakistan.
"Without the participation of Pakistan, any peace process will not see a fruitful end," he said.
U.S. officials 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)