MAZAR-I-SHARIF, Afghanistan (Reuters) - Taliban fighters are threatening major oil wells near the northern Afghan city of Sar-e Pul following days of fighting in which dozens of members of the security forces have been killed and wounded, officials and residents said on Friday.

“The security situation in Sar-e Pul province is alarming,” said Zabiullah Amani, the provincial governor’s spokesman.

“We have had promises that reinforcements would be sent to the city but nothing has been done yet,” he said.

About 40 members of the security forces were killed or wounded near Sar-e Pul on Tuesday during hours of fighting that underlined the heavy pressure Afghan government forces are facing even as moves towards peace have intensified.

“The Taliban have been launching major attacks for some time with the aim of securing these oil fields and we’ve set up a special protection force but they don’t have advanced equipment,” Amani said.

The wells in the Angot field, about 11 km east of Sar-e Pul city and Kashkari, 12 km to the south, were developed during the Soviet presence in Afghanistan.

Amani said eight wells were active, with millions of dollars’ worth of military equipment, including armored vehicles stored close by.

“These wells are economically important, not just for the province of Sar-e Pul but for the whole of Afghanistan,” he said.

The capture of the wells would deliver a blow to the government and bolster Taliban finances, adding to revenues from taxation, mining and opium.

An aide to interior minister Amrullah Saleh said additional forces had been sent to the oil fields from neighboring districts and a team from Kabul would be sent in coming days.

“As of now, the area is secure but we cannot deny the threat warning,” he said, adding that companies operating the wells had been alerted.

The fighting comes as another round of talks is expected between U.S. special envoy Zalmay Khalilzad and Taliban representatives to try to work out the basis for peace talks to end the 17-year Afghan war.

With U.S. intentions unclear following reports that President Donald Trump is preparing to withdraw almost half of the estimated 14,000 U.S. troops from Afghanistan, pressure on Afghan forces has been mounting.

Hekmat Haidari, a resident of Sar-e Pul city, said the situation in the province had been deteriorating sharply over recent days as the Taliban have stepped up operations.

“The oil wells in this province are a major source of income for Afghanistan and specially for Sar-e Pul province and the Taliban are trying to capture these wells or to destroy them,” he said.