Fighting in Afghanistan's south left 12 suspected Taliban and eight police dead, while a roadside bomb Thursday killed an Afghan civilian in an eastern province, officials said.

The roadside bomb went off in Jalalabad Thursday morning while Lt. Gen. Karl Eikenberry — the top U.S. general in Afghanistan — visited a U.S. base in the city.

The Interior Ministry said one Afghan civilian died. Dr. Ajmel Pardes, health chief for Nangahar province, said seven civilians were wounded, three critically.

U.S. military spokesman Col. Tom Collins said the general had not traveled the road where the bomb exploded and that it was unlikely he was the target. Collins said the general was at a U.S. provincial reconstruction team base in Jalalabad at the time, and only visited the site of the blast two hours later.

"We were at a PRT in Jalalabad receiving a briefing when the blast occurred," Collins said. "We were nowhere near it."

Afghanistan has seen an upsurge of violence this year, particularly in the south where rebel supporters of the Taliban regime have stepped up attacks. Afghan and NATO-led troops are trying to drive insurgents out of their safe havens, triggering the bloodiest fighting in nearly five years.

CountryWatch: Afghanistan

In Kandahar province, Taliban rebels and police fought for about 90 minutes on Tuesday in Panjwayi district, until the rebels fled, taking their dead and wounded, said provincial government spokesman Dawood Ahmadi.

Twelve militants and eight policemen were killed; nine militants and seven police were wounded, he said.

In southeastern Paktika province, a roadside bomb on Wednesday killed two Afghan soldiers and wounded three in Waza Khwa district as they returned after a mission to help police surrounded by insurgents, said Defense Ministry spokesman Gen. Mohammad Zahir Azimi.

Meanwhile, in the eastern province of Nuristan, one of the country's wildest regions, U.S. soldiers and warplanes drove off an insurgent attack early Wednesday on a new American base, killing 19 militants, U.S. Maj. Tom Sutton said.

The raid on the U.S. base at Kamdesh was staged by extremists likely belonging to the Hezb-e-Islami militant group of renegade Afghan warlord Gulbuddin Hekmatyar, the military said. The militants attacked from three directions out of forests using rocket-propelled grenades and small-arms fire.

Several hundred soldiers at the base, which lies in a small town but backs onto a sheer mountain face, returned fire with mortars and small arms before jets dropped four 500-pound bombs, ending the clash, which lasted more than two hours.

The region is a stronghold of Hekmatyar, who has ties with Usama bin Laden and now fights President Hamid Karzai's government. His fighters are also supported by loyalists of the Taliban regime.

Karzai, whose popularity has declined because of slow progress in rebuilding the war-battered country and poor security, signaled in an interview with Fortune magazine this week that he won't run for president again in elections slated for 2009.

Karzai was named Afghanistan's transitional leader soon after the Taliban's ouster, then became its first democratically elected president in late 2004 for a five-year term.