Updated

An Afghan official says an attack at a police checkpoint in the country's west has killed four people, two policemen and two civilians.

Administrative district chief Mohammad Rafiq Alokozay says gunmen opened fire and lobbed hand grenades at the checkpoint in Obey district in Herat province on Tuesday.

Alokozay says the attack on the checkpoint, which is located near a bazaar, also wounded seven other people, two policemen and five civilians.

No one immediately claimed responsibility for the attack but the Taliban have stepped up their summer offensive against Afghan security forces in a bid to undermine the Western-backed government as foreign combat troops prepare to withdraw by the end of the year.