Five policemen were killed by a roadside bomb in eastern Afghanistan, and 28 Taliban fighters were killed in separate military operations, officials said on Saturday.

The bomb struck a border police vehicle in Durbaba district of Nangarhar province near Pakistan, killing all five policemen, Ahmad Zia Abdulzai, the provincial governor's spokesman, said.

No group claimed responsibility.

The military claimed to have killed 27 rebel fighters in the southern province of Helmand in the last two days.

Local government spokesman Daud Ahmadi said 17 insurgents were killed by Afghan troops in Nad Ali, Nahr-e-Saraj and Greshk districts.

"Eleven other insurgents were killed during an operation of NATO-led forces in another area of Greshk district as they were preparing to attack police checkpoint," he said.