Seven people have died and dozens have been injured when a passenger train travelling through southern India collided with another train halted at a signal.

Airstrikes by Nato helicopters hunting Taliban fighters ripped through three dried mud homes in southern Afghanistan as villagers slept, killing at least nine civilians, including women and children, said residents and the provincial governor.

Police may have killed a suspected top al Qaida operative today in a four-hour gun battle at a house in southern Pakistan that also led to the arrest of two other men.

Four militants armed with grenades who were allegedly planning suicide attacks have been arrested in Karachi, Pakistani police said.