Up to six Afghan army soldiers were killed on Monday in a roadside bombing in the county's eastern province of Kapisa, sources said on Tuesday.

"A line of army vehicles were returning after they ended an operation in the mountainous Alasay district late Monday. One army van set off an improvised explosive device, causing six army soldiers killed," a provincial security official told Xinhua.

He said the vehicle was destroyed in the attack in the province 65 km of the national capital Kabul.

Several militants were also killed and wounded following the above raid, he noted.

In a separate incident, four militants were killed and four others wounded in an airstrike conducted by the security forces in Naw Zad district of southern Helmand province overnight, the district governor Sayyed Murad Sadat told Xinhua earlier on Tuesday.

The militants set up an illegal checkpoint and terrorized the locals, before they came under attack, the official noted.

The Taliban insurgent group has intensified attacks recently as the Afghan army and police took the full operational lead from foreign troops in June last year. The war-torn country is due to take over the responsibility for its own security from foreign troops by the end of the year.