A roadside bomb in western Afghanistan and clashes in the volatile south left eleven police officers dead.

A roadside bomb in western Afghanistan and clashes in the volatile south left eleven police officers dead, officials said Tuesday.

The bomb killed six police guards in Herat province on Tuesday as they travelled to a hydroelectric dam that is under protection from insurgent attack.

The officers were from the Afghan Public Protection Force, a government-run force that provides security for international supply convoys, aid groups and foreign-funded reconstruction sites.

There was no claim of responsibility but similar bombs are often blamed on the Taliban, the main militant group waging an insurgency against the government in Kabul.

Taliban insurgents attacked several police posts in the southern province of Helmand on Monday, triggering two days of clashes at the start of the traditional fighting season.

The interior ministry spokesman in Kabul said about 100 insurgents were involved in the offensive in the tinderbox district of Sangin, with five police and 26 militants killed.

The NATO-led International Security Assistance Force (ISAF) said none of its soldiers were involved in the fighting and put the number of attackers at less than 50.

Sangin district has been a hotspot of fighting for several years, with British and US forces battling against Taliban insurgents.

Afghan soldiers have recently taken over increased responsibility across the country as 100,000 ISAF troops start to gradually withdraw from the battlefield ahead of the end of combat missions next year.