Kabul -  Gunmen killed a tribal elder and his son in an attack in southern Afghanistan, while elsewhere at least 22 insurgents were killed and eight others were detained in separate operations by Afghan and international forces, officials said Saturday.

Gunmen on motorbike shot Ali Ahmad Barekzai and his son as they were leaving a mosque in southern Kandahar's provincial capital on Saturday morning, said Zelmai Ayoubi, spokesman for the provincial governor.

Barekzai's son Gul Ahmad had served as Afghan President Hamid Karzai's bodyguard, and officials believed he could have been the prime target.

Karzai condemned the "cowardly attack" on Barekzai and vowed to bring the perpetrators to justice.

"Afghan culture and religion does not permit this kind of barbaric and an-Islamic action. No Muslim would commit murder inside a mosque," Karzai said in a statement.

Taliban have increased their attacks inside Kandahar city, which until recently was one of their strongholds. The rebels also killed a senior female police officer in Kandahar late last month.

Attackers on motorbike killed another provincial official in the city last week.

Afghan and NATO forces engaged Taliban militants in two separate operations in Wardak province on Thursday night, killing 19 rebels, the alliance said in a statement.

The operation employed heavy weapons and helicopters in the Jalrez and Nerkh districts of the province, which is located west of Kabul city.

In another incident, insurgents fired rockets on an Afghan army base in Narang district of eastern Kunar province on Friday, causing no casualties, the defence ministry said in a statement.

It said the army forces replied the attacks with heavy artillery fire and killed several insurgents including three Taliban local commanders.

US-led coalition forces detained eight militants in multiple operations in southern Ghazni province, the US military said in a statement.

Taliban-led attacks are on the rise in the country despite the presence of around 70,000 international troops, who have been deployed to Afghanistan to support Karzai's government.

More than 4,000 people - mostly insurgents - have been killed in Afghanistan conflict so far this year. (dpa)