Fierce fighting between Taliban rebels and Afghan security forces left 18 insurgents and three others dead, a day after the US military pounded suspected rebels in airstrikes that killed as many as 20, officials said today.

A Taliban spokesman, meanwhile, claimed his fighters had assassinated a kidnapped Afghan police chief and five of his men for collaborating with the US-led coalition.

Eleven rebels were killed in an hour-long firefight before dawn today after attacking a government office in the Washer district of Helmand province, said Haji Mohammed Wali, a spokesman for the governor. The district government chief and an Afghan soldier also died.

Another seven rebels were killed overnight and early today after they attacked a police checkpost on a stretch of the Kabul-Kandahar highway that runs through southern Zabul province, said Zabul’s deputy police chief, Bari Gul. A policeman manning the post was also killed.

Three months of bloodshed across the south and east has left hundreds dead and sparked fears that the Afghan war is widening, rather than winding down. US and Afghan officials warn things could get worse ahead of landmark parliamentary elections scheduled for September.

About 280 suspected rebels and 29 US troops have been killed since March, according to Afghan and US officials. More than three dozen Afghan police and soldiers also have died, as have more than 100 civilians.

Yesterday, US aircraft opened fire on a group of suspected Taliban along a narrow footpath in the high mountains north west of Gereshk, in southern Helmand province, after rebels had pinned down a coalition ground patrol with rocket and small-arms fire.

“Initial battle-damage assessments indicate 15 to 20 enemies died and an enemy vehicle was destroyed,” the US Army said in a statement last night. No Americans were injured.

Elsewhere in Helmand on Sunday, gunmen shot to death three men – a judge, an intelligence worker and an employee of the provincial education department, said Wali, the governor’s spokesman.

Purported Taliban spokesman Mullah Latif Hakimi claimed responsibility for the ambush of a police convoy in southern Afghanistan earlier this week and said insurgents had killed a district police chief and five of his men after taking them captive.

Hakimi said five other officers captured in the ambush were alive. He said the men would face a trial.

Hakimi often calls news organisations to claim responsibility for attacks on behalf of the Taliban. His information has sometimes proven untrue or exaggerated and his exact tie to the group’s leadership is unclear.