The strike in a village in Takhar province came Wednesday after suspected Taliban fighters targeted Afghan security forces in the area.

According to provincial police spokesman Khalil Aseer, an air strike that came during the fighting hit a mosque, killing 12 people including 11 youngsters.

"The air strike was carried out when the victims were busy studying the Holy Koran," Aseer said, adding a prayer leader was among the dead. He did not give the ages of any of those killed.

Fourteen other people, including children, were wounded in the strike, Aseer said. Takhar provincial governor spokesman Mohammad Jawad Hejri confirmed the incident.

It was not clear who conducted the air strike. The US military referred a query to the Afghan defence ministry, which did not immediately comment.

The Afghan military has a fledgling air force and small attack planes capable of conducting close-air support for troops on the ground.

Vice President Amrullah Saleh said no minors had been killed at the mosque.

"The news of children killed in a mosque in Takhar is baseless," he wrote on Facebook.

"We have undeniable evidence that those who killed our security forces ... were killed. Those who spread rumours will be dealt legally."

Heavy fighting with the Taliban in Takhar since Tuesday has left at least 25 security personnel dead.

Despite joining peace talks with the Afghan government in Qatar last month, the Taliban have only increased violence in a bid to wield leverage in the negotiations.

The top US envoy to Afghanistan, Zalmay Khalilzad, said earlier this week that fighting is threatening the peace process.