SAR-E PUL, Afghanistan (Reuters) - Afghan village elders are trying to arrange the release of around 150 families held by Taliban fighters in a remote area of the northern province of Sar-e Pul while they await for security forces to arrive, officials said on Tuesday.

Provincial governor Zahir Wahdat said authorities were still waiting for the arrival of reinforcements to retake Mirza Olang village, which was overrun by insurgent fighters at the weekend with as many as 50 local people killed.

“We have a limited number of forces who are only able to defend their areas when there is an attack until they get reinforcements,” he said.

“We have sent some people including elders and people from Mirza Olang area to convince the Taliban to free around 150 captured families and give us the dead bodies of villagers,” he said. Government forces would launch a “massive operation” to get the district back if that approach failed, he said.

According to locals who arrived in the provincial capital Sar-e Pul, a large insurgent force attacked the village where local informal militia forces had been inflicting heavy casualties on the Taliban for months.

Some 330 families had escaped the area after warnings from the Taliban but most of the civilians killed in the incident died while trying to leave.

President Ashraf Ghani promised “revenge” for the attack but the incident underlines the precarious security situation across much of Afghanistan, where militant and bandit groups defy central government authority in many areas.

According to U.S. military estimates, only 60 percent of the country is in government hands with the rest either controlled by the Taliban or left in a limbo outside of either insurgent or government control.

Local officials said the Mirza Olang attack, one of the most serious of its kind for some time, was carried out by Taliban and Islamic State militants operating together.

The Taliban has rejected that allegation, saying a group under one of its commanders carried out the attack. However, local villagers reported seeing fighters carrying both the white banner of the Taliban and the black banner of Islamic State.

The Taliban, fighting to install strict Islamic law and drive foreign forces out of Afghanistan, has fiercely opposed the local version of Islamic State since its appearance in Afghanistan in 2015.

But any sign of the two groups joining forces would alarm Western governments concerned that as insecurity rises in Afghanistan, the country could once again become a base for militant groups aiming to strike foreign targets.