MAZAR-I-SHARIF, Afghanistan (Reuters) - Dozens of families displaced from their homes in the northern province of Sar-e Pul by Taliban pressure have arrived in the provincial capital, as the insurgents have tightened their grip around the city, residents and officials said.

Taliban fighters have been threatening oil fields around the city of Sar-e Pul as they have stepped up operations with the apparent aim of strengthening their position during peace talks with U.S. officials.

“In general, the security situation in Sar-e Pul province has been in critical condition and the Taliban are trying to carry out their attacks on the districts close to the city,” said Zabiullah Amani, spokesman for the governor of Sar-e Pul.

The fighting comes as peace talks between U.S. special envoy Zalmay Khalilzad and Taliban representatives have stalled over the insurgents’ demand to focus the agenda for peace talks on the withdrawal of U.S. troops from Afghanistan.

The increasingly confident Taliban now control broad swathes of the countryside outside the main cities of Afghanistan and have set their stamp ever more clearly on areas under their control as government forces struggle to push them back.

In Sar-e Pul, officials said around 40 families had arrived in the provincial capital from Kohistan, an isolated district firmly under Taliban control, and have mostly been seeking shelter from the freezing winter temperatures in city mosques.

With punishing winter temperatures making life a misery for displaced people, little help has come from the government.

“These families are now in the center of the city of Sar-e Pul and are in a very bad state because they do not have any kind of living materials,” Amani said.

Accounts from the displaced families suggest the Taliban singled out families believed to have sympathies with the government or family members in the police and expelled them.

Haji Azizullah, an elder who oversaw the transfer of displaced families from Kohistan district, said those driven from their homes were all suspected of being close to the military or the security forces.

“The Taliban told us to either take your children and work together with the Taliban under our authority or move you out of this area,” he said.

With the Taliban still refusing to talk directly with the Afghan government, the pressure on families on the opposing side points to some of the likely problems in any post-settlement Afghanistan after more than 17 years of war.

Saber, a resident of Kohistan who left the district with her six children last week, said Taliban had approached her a week ago and told her to bring her son, a member of the Afghan Local Police, in to them.

“When I refused, four people from the Taliban came yesterday and told me I had to get out of the area,” she said.

The Taliban spokesman was not immediately for comment.