* Protocol spat snarls revived peace bid
* Exchange of captives expected to be discussed
By Amena Bakr
DOHA, June 20 (Reuters) - A fresh effort to end Afghanistan's 12-year-old war looked in disarray on Thursday after a diplomatic spat about the Taliban's new Qatar office delayed preliminary discussions between the United States and the Islamist insurgents.
Talks between U.S. officials and representatives of the Taliban had been set for Thursday in Qatar but Afghan government anger at the fanfare surrounding the opening of a Taliban office in the Gulf state threw preparations into confusion.
The squabble may set the tone for what could be long and arduous negotiations to end a war that has raged since the U.S. invasion of Afghanistan that followed the Sept. 11, 2001 al Qaeda attacks on U.S. targets.
Asked when the talks would now take place, the source in Doha said "There is nothing scheduled that I am aware of." Asked if that meant they would not happen today, the source added: "Yes that's correct."
The opening of the office was a practical step paving the way for peace talks. But the official-looking protocol surrounding the event raised angry protests in Kabul that the office would develop into a Taliban government-in-exile: A diplomatic scramble ensued to allay their concerns.
A Taliban flag that had been hoisted at the Taliban office on Tuesday had been taken down and lay on the ground on Thursday, although it appeared still attached to a flagpole.
A name plate, inscribed with the title "Political Office of the Islamic Emirate of Afghanistan" had also been removed.
Questioned whether the Taliban's office in Doha had created a sense of optimism about peace efforts, the source replied: "Optimism and pessimism are irrelevant. The most important thing is that we now know the Taliban are ready to talk, and sometimes talk is expensive."
Word of the U.S.-Taliban talks had raised hopes that Karzai's government and the Taliban might enter their first-ever direct negotiations on Afghanistan's future, with Washington acting as a broker and Pakistan as a major outside player.
The Taliban has until now refused talks with Kabul, calling Karzai and his government puppets of the West. But a senior Afghan official said earlier the Taliban was now willing to consider talks with the government.
In its talks with the U.S. officials, the Taliban was expected to demand the return of former senior commanders now detained at the U.S. military prison at Guantanamo Bay, Cuba, a move opposed by many in the U.S. Congress, as well as the departure of all foreign troops.
The United States wants the return of the only known U.S. prisoner of war from the conflict, Sergeant Bowe Bergdahl, who is believed to be held by the Taliban.
The protocol dispute burst into the open on Wednesday when Afghan President Hamid Karzai said his government would not join U.S. talks with the Taliban and would halt negotiations with Washington on a post-2014 troop pact.
Officials from Karzai's government, angered by the official-sounding name the Taliban chose for its political office in Doha, said the United States had violated assurances it would not give official status to the insurgents.
Afghan government officials objected to the impression that the insurgents had achieved some level of international political recognition and could use it as an official embassy or even as a base for a government-in-exile.
"As long as the peace process is not Afghan-led, the High Peace Council will not participate in the talks in Qatar," Karzai said in a statement, referring to a body he set up in 2010 to seek a negotiated peace with the Taliban.
A statement on Qatar's foreign ministry website late on Wednesday clarified that the office which opened was called the "Political Bureau for Afghan Taliban in Doha".
The source familiar with the matter said: "The Taliban have to understand that this office isn't an embassy and they are not representing a country."
The dispute over the Taliban office after months of behind-the-scenes diplomacy to restart the peace talks underscored what U.S. officials say is a void of trust between Karzai and the Taliban, who have been waging an insurgency to overthrow his government and oust foreign troops.
Fighting continued in the war-ravaged nation. Four U.S. soldiers were killed in a rocket attack on the heavily fortified Bagram base near Kabul late on Tuesday, international military officials said.
U.S. and Afghan officials said U.S. Secretary of State John Kerry spoke with Karzai on Tuesday night and again on Wednesday morning in an effort to defuse the controversy.
Underlining the importance of the process to the United States, the State Department said Kerry would travel to Doha for meetings with senior Qatari officials on Friday and Saturday. But U.S. officials said he would not meet with Taliban representatives.