The Afghan government on Wednesday lashed out at US efforts to broker peace with the Taliban, suspending crucial security talks with Washington and threatening to boycott prospective contacts with the insurgents in Qatar.
Kabul issued two strongly worded statements threatening to sabotage US efforts to start talks with the Taliban, just one day after its foes opened an office for dialogue in the tiny Gulf emirate.
With the US-led NATO combat mission due to end next year, US officials are determined to resume talks with the Taliban after tentative contacts limited to a prisoner swap collapsed last year.
But President Hamid Karzai, who has headed the US-backed Afghan government since a 2001 US-led invasion brought down the Taliban, opposes bilateral US-Taliban talks.
On Wednesday he broke off ongoing Afghan-US talks on an agreement that would allow Washington to maintain soldiers in Afghanistan after a NATO combat mission ends next year.
Hopes of peace were given a further reality check when the Taliban claimed an overnight rocket attack that killed four US troops at the largest US-led military base in Afghanistan.
In response to the talks suspension, US President Barack Obama said he always expected "friction" at Afghan reconciliation talks but voiced hope that "despite those challenges the process will proceed".
But Karzai's spokesman Aimal Faizi told AFP there was a "contradiction between what the US government says and what it does regarding Afghanistan peace talks".
The row centred on the Taliban office calling itself the "Islamic Emirate Of Afghanistan" -- the formal name of its 1996-2001 government -- on the grounds that no such thing existed, officials said.
A follow-up statement from Kabul threatening to boycott prospective talks in Qatar unless they were "Afghan-led" exposed a wider rift and outright criticised the US involvement.
"The latest developments show that foreign hands are behind the Taliban's Qatar office and, unless they are purely Afghan-led, the High Peace Council will not participate in talks," it said.
The High Peace Council is the government body in charge of leading peace efforts with the Taliban.
"The opening of Taliban office in Qatar, the way it was opened and messages it contained, contradicts the guarantees given by the US to Afghanistan," the statement said.
Troubled relations between Karzai and Washington have degenerated into public spats in the past, but many Afghans also reacted with scepticism to news that the Taliban could be ready to enter peace talks.
"It is a historic mistake by the US government, recognising and giving legitimacy to a terror network who are killing every single day Afghan civilians, women and children," Shukria Barakzai, a moderate female lawmaker told AFP.
Karzai initially seemed to embrace the opportunities presented by the opening of the Taliban office in Qatar on Tuesday, when NATO formally transferred responsibility for security to Afghan forces.
About 100,000 foreign combat troops, 68,000 of them from the US, are due to withdraw by the end of next year.
But a continued American military presence is considered vital to support the Kabul government, hence the security talks now suspended.
The Taliban have said only their new office would "open dialogue between the Taliban and the world", but made no direct reference to peace talks.
Office spokesman Mohammed Naim said Qatar will be a mediator in negotiations. "We trust Qatar's capability and expertise in dealing sincerely with regional conflicts," he said.
But a divided insurgency is likely to complicate talks, amid doubts as to whether the Haqqani network of warlord Jalaluddin Haqqani, a former CIA asset turned Al-Qaeda ally, is ready to embrace dialogue.
A Taliban spokesman in Qatar, Mohammad Sohail Shaheen, confirmed that the armed group would continue to attack US targets in Afghanistan at the same time as holding any talks.
"There is no ceasefire (with the US) now. They are attacking us and we are attacking them," Shaheen told Al-Jazeera news channel.
Obama has insisted the Taliban will have to renounce ties to Al-Qaeda, halt violence and commit to the protection of women and minorities. He has warned that NATO forces remained "fully committed" to battling Al-Qaeda.
The Taliban were driven from power by US-backed rebels after the September 11, 2001 attacks. They have since mounted a guerrilla war against the Afghan government and maintain rear bases in Pakistan.
A US official has said American and Taliban envoys would meet in Doha "in a couple of days", after which the Taliban would meet Afghan peace envoys.
In opening their mission, the Taliban did not explicitly renounce Al-Qaeda, which they refused to expel after the 9/11 attacks, but did vow to prevent attacks being launched from Afghanistan.