Afghan police say are holding a man suspected of attempting to assassinate President Hamid Karzai on a trip to the former Taleban stronghold of Kandahar.
President Karzai wants moderate Taleban to take part in elections
The suspect was arrested with a grenade close to a road where the president's convoy was due to pass, police said.
Mr Karzai visited the southern city to invite elements of the Taleban to help rebuild the country and take part in the forthcoming national election.
He said his offer extended to all but a few hardcore Taleban members.
"Our problem is mainly with the top Taleban - who may number no more than 150 people - who had links with al-Qaeda," he said. "Those people are the enemies of Afghanistan and we are against them.
"But those Taleban who are doing jobs and tilling the fields and working as shopkeepers, we want to welcome those Taleban."
He said the government had been negotiating with less radical Taleban leaders for some months.
The Afghan leader was speaking from Kandahar - the focus of recent attacks by the Taleban.
It was his first visit since an attempt on his life there in September 2002, when a guard opened fire on his car as he was leaving the governor's residence.
Security officials said on Sunday that a further assassination attempt may have been foiled after the arrest of a man with a grenade.
The suspect was seized a few minutes before the president's convoy was due to pass by, provincial military spokesman Abdul Lali told AFP news agency.
"The individual was hiding behind a house close to the road," he said.
A source close to the presidency told AFP only that a "minor incident" had occurred.
Security was tight during the president's visit, with the area around the governor's residence - where Mr Karzai was staying - blocked off.
AFP said US helicopters provided surveillance from the air.
Taleban have stepped up attacks in recent weeks, with several bombings reported in Kandahar.