Afghanistan's Taliban insurgents warned Thursday that their support of peace talks did not mean they had given up fighting or accepted the constitution of the "stooge" government in Kabul.

The comments came as the United States announced that it would send a senior official to meet Afghan President Hamid Karzai next week to see whether he agrees to a resumption of preliminary talks with the Taliban.

A US official said the talks could open within weeks if Karzai was agreeable.

The Taliban, who have announced plans to open a political office in Qatar, said they had "increased our political efforts to come to mutual understanding with the world" to bring about peace in Afghanistan.

"But this understanding does not mean a surrender from jihad and neither is it connected to an acceptance of the constitution of the stooge Kabul administration," the hardline Islamists said in a statement received by AFP.

"But rather the Islamic Emirate is utilising its political wing alongside its military presence and jihad in order to realise the national and Islamic aspirations of the nation and its martyrs."

Taliban acceptance of the Afghan constitution is a key demand of the US for progress in any peace talks, along with a renunciation of violence.

US Secretary of State Hillary Clinton said that US special regional envoy Marc Grossman would visit Kabul next week and several other key regional capitals to discuss the peace process.

Washington has consistently said that any talks with the Taliban to end the decade-long war could only take place with the agreement of the Afghan government which eventually should lead the process.

Clinton, after meeting Qatari Prime Minister Sheikh Hamad bin Jassim al-Thani in Washington on Wednesday, said "positive statements" from Karzai and the Taliban signaled support for discussions on opening a political office in Qatar.

The top US diplomat cautioned, however, that nothing had been decided on the idea of a Qatar office for the Taliban and that Washington and its allies were still in the preliminary stages of testing whether the approach could be successful.