Taliban militants killed at least 22 security forces, including a district police chief, in separate attacks on security checkpoints in two Afghan provinces, officials said on Sunday, ahead of parliamentary elections set for this week.

The Taliban have ramped up attacks in strategic provinces in their battle to expel foreign forces and topple the Western-backed government.

The police chief of Mizan, a district in southern Zabul province, was killed in armed clashes with Taliban insurgents on Saturday night, said Rahmatullah Yarmal, the provincial governor.

In the western province of Farah, Taliban fighters killed 21 troops at two checkpoints in the district of Posht-e Rud.

The Taliban captured 11 soldiers and seized their weapons, said Gul Ahmad Faqiri, a member of the Farah provincial council.

The hardline Islamist militant group claimed the attacks.

Last week the Taliban ordered Afghans to boycott the elections, set for October 20, saying the United States was using them for the sole purpose of legitimizing its authority and presence in the country.

The vote, seen by the Afghan government's international partners as a dry run for presidential elections next year, has been hampered by chaotic preparations, allegations of fraud and ever-present fears of militant violence.