Updated

President Hamid Karzai said Monday that if he wins re-election as Afghan president this month he will invite Taliban and other militants to a grand tribal council — but said they would have to lay down their weapons first.

His invitation came despite the latest, bold militant assault on an Afghan city. At least four Taliban fighters infiltrated the capital of Logar province, just south of Kabul, and fired rocket-propelled grenades at government buildings. Two police and four attackers died in the violence.

Such attacks have deepened fears for the security of the Aug. 20 elections — the second presidential vote since the ouster of the Taliban regime in 2001. Insurgents, who have escalated their violent campaign this year, are threatening to sabotage the vote.

Karzai on Monday unveiled his election platform and said that if he wins a second term he will invite the Taliban and the Hezb-e-Islami militant faction to lay down their weapons and join him in a grand meeting known as a loya jirga, a revered form of negotiation in Afghanistan's deeply tribal society.

Karzai has repeatedly called for peace talks over the years but never in the form of a loya jirga — the means by which Afghanistan's post-Taliban constitution was approved.

Taliban chief Mullah Omar has said, however, the Taliban won't participate in peace talks until foreign troops leave the country.

On Monday, militants penetrated Pul-i-Alam, about 40 miles (60 kilometers) south of Kabul. They fired four RPGs at the Logar provincial governor's compound and two at the police chief's office, said Din Mohammad Darwesh, the governor's spokesman.

The militants took up positions in a building behind the governor's house and were surrounded by Afghan soldiers and police, he said.

After the rockets were fired, a gunbattle broke out between Afghan forces and the militants, said Mustafa Musseini, the provincial police chief. Two Afghan police officers were killed, he said.

U.S. helicopters patrolled the skies, and one fired a rocket at an attacker, killing him, Musseini said. Another attacker blew up a suicide vest and killed himself, and two other attackers died in battle, Musseini said.

A Taliban spokesman, Zabiullah Mujahid, said six militant suicide bombers had entered Pul-i-Alam. Afghan officials said four had.

The NATO-led force said that Afghan and NATO troops found explosives rigged to detonate in the building from which militants launched their attack. The NATO troops — most troops in Logar are American — "worked to render the explosives and the area safe," a NATO statement said. NATO said one Afghan child was wounded by the militants' initial assault.

Taliban militants have launched several multi-pronged attacks on eastern Afghan cities in recent months. The militants typically attack multiple sites at once with rockets, gunfire and suicide explosions.

Violence has spiked the last three years, and a record number of U.S. and NATO troops are now in the country. Afghan and international troops are trying to increase security ahead of the election.

In his comments Monday, Karzai called for the Afghan army to be increased from its current target of about 130,000 forces to 260,000 forces, and for police numbers to rise from 80,000 to 160,000 over the next five years. Afghanistan currently has 83,000 police and 92,000 soldiers.

The U.S. and other NATO nations are now studying how many soldiers and police to add to Afghanistan's security forces, which are primarily funded by the U.S.

Elsewhere, six Taliban militants died after a roadside bomb they were planting exploded prematurely.

The militants were planting the bomb around 3 a.m. Monday in the Naw Bahar district of southern Zabul province when the bomb exploded, said local official Abdul Zarif.

Militants have greatly increased their use of roadside bombs in Afghanistan this year. A record number of U.S. and NATO troops were killed in the country in July, many of them from roadside bombs.

Also Monday, Afghanistan's Interior Ministry said a suicide bomber attacked coalition forces in the northern province of Kunduz. No one besides the bomber was wounded or killed.