QUETTA: About a dozen gunmen in Pakistan's southwestern district of Mastung attacked and set fire to some 19 trucks carrying fuel for Nato forces in Afghanistan, DawnNews reported.

There were no reported casualties.

The militants have frequently targeted Nato supply trucks over the past few years, but attacks have intensified since the killing of al Qaeda chief Osama bin Laden by US special forces in a secret raid in a Pakistani military town on May 2.

Five Nato trucks were set ablaze in the same region on Friday.

Routes through Pakistan were until recently bringing in 40 per cent of supplies for Nato forces, with another 40 per cent coming through Afghanistan's neighbours in the north and 20 per cent by air.