A suicide car bomb has killed five Afghan civilians and injured 19 others, Afghan sources say, amid continued fighting between multinational troops and Taliban fighters.

The explosion took place on Monday near a convoy of international forces in western Afghanistan, Zemarai Bashary, an interior ministry spokesman, said.

"A suicide car bomb exploded. Four civilians were killed and 12 others were injured. The target was a foreign forces' convoy," he said.

The condition of the foreign soldiers after the blast, which took place in the Shindand district of Herat province, was not immediately known.

The explosion occurred on the same day that US-led forces said they killed 55 Taliban fighters, including three senior commanders.

The deaths resulted after the fighters attacked a patrol of the US-led force with rockets in the Paktika province, near the eastern Afghan-Pakistani border.

Nangarhar incident

The incidents came a day after a father and son were allegedly killed by gunfire from US-led soldiers in Khogyani district of the eastern Nangarhar province.

US-led and Afghan forces hit a private house after firing on a neighbouring suspected opposition hideout, Haji Zalmai Khan, Khogyani's governor, said.

The deaths later prompted about 200 residents to take to the streets in protest.

The multinational forces, however, denied any civilian casualties.

In another incident on Sunday, air strikes conducted after a Taliban attack killed several fighters in southern Afghanistan, US-led forces said.

Violence surge

The Taliban in Pakistan have recently claimed a number of successes, killing seven foreign troops over the weekend, while violence has surged this month.

The group caused a jail-break of more than 1,000 prisoners on June 14, when suicide bombers attacked Kandahar prison in southern Afghanistan.

Many of those who escaped were Taliban members.

Afghan and Nato forces reacted by launching a major operation to expel Taliban fighters from villages surrounding Kandahar a few days later. Afghan officials said that the operation killed 56 Taliban fighters.