Afghan President Hamid Karzai launched a peace plan on Wednesday that he hopes will persuade Taliban fighters to lay down their arms, but the insurgents demonstrated their disdain by firing a rocket as he addressed a traditional gathering in the capital.

Unpopular at home despite an election victory last year that was mired in controversy, Karzai called a 'jirga' of tribal leaders, elders and other notables to forge national consensus for overtures to the Taliban.

But minutes after he began unveiling his plans, a rocket landed in an open field near the giant marquee where the event was being held. There were no immediate reports of casualties.

'Sit down, nothing will happen,' Karzai told nervous delegates as some stood to leave.

'I have become used to this,' said Karzai, who has survived at least three assassination attempts. 'Everyone is used to this.'

The sound of gunfire could also be heard around the venue as Karzai finished his speech and left in a convoy of armoured vehicles.

The peace jirga, as the centuries-old gathering is known in Pashto, has drawn 1,300 delegates, but noticeably absent will be representatives of the insurgents -- although there will certainly be sympathisers.

With the insurgency at its most intense since their US-led overthrow in 2001, the Taliban remain confident they can outlast the latest foreign invasion in Afghanistan's long history of conflict.

'Obviously, the jirga will provide yet another pretext for America to continue the war in Afghanistan, rather than bringing about peace in the country,' the Taliban said in a statement on the eve of a gathering to which they had not been invited, but would not attend if asked.

Their confidence comes despite a surge in US forces that will push the size of the foreign military to around 150,000, with an offensive planned in coming weeks to tackle the Taliban in their southern heartland of Kandahar.

But following its rapid disengagement from Iraq, the United States is keen, too, to get out of Afghanistan, and President Barack Obama has said he wants to start withdrawing troops from July 2011.

Washington is also stressing an accompanying hearts-and-minds operation that it hopes will see better Afghan security and governance put in place. Corruption and incompetence by some  officials have caused open friction with Karzai at times.

As a result, some diplomats and analysts are paying lip service to the jirga's noble aims while doubting its effectiveness. Competing interests from Pakistan, India, Iran and even Russia further poison the atmosphere.

'This is a big week for Afghanistan,' said Mark Sedwill, Nato's top diplomat in the country.

The man Karzai beat for the presidency last year, Abdullah Abdullah, dismissed the jirga out of hand, although he said he would not call for a boycott.

'The outcome of the jirga will not take us anywhere towards peace, even not close to it,' Abdullah said.

'The agenda is not known to people, the norms are not known, people invited to the jirga do not represent the people. This event sounds to me like a PR exercise.'

The key points of Karzai's plan call for an amnesty for rank-and-file Taliban who renounce the insurgency and agree to the constitution. To encourage them, they would be offered training and jobs on development projects in their home areas.

He also wants the names of certain Taliban officials removed from a UN blacklist and for others to be allowed to seek sanctuary in a friendly Muslim country. This would allow him to seek a more direct approach to the leadership. – Reuters