KABUL (Reuters) - Security forces clashed with Taliban fighters in key locations in northern Afghanistan on Monday, with dozens of people killed and the city of Sar-e Pul threatened by insurgents, officials said.

Fighting has raged around the provincial capital of Sar-e Pul for two days and at least 17 members of the security forces have been killed in the past 24 hours, according to the provincial governor’s spokesman Zabihullah Amani.

He said the figure was provisional and the real number of casualties may be higher.

The increasingly fragile situation in the north presents a major early challenge to Gen. Scott Miller, the new commander of U.S. and coalition forces in Afghanistan, who took up his post earlier this month.

U.S. officials have pressed for talks with the Taliban and recently appointed former ambassador Zalmay Khalilzad as special representative to try to push the peace process forward.

Last month, Taliban forces briefly overran the strategic city of Ghazni, on the main highway between Kabul and southern Afghanistan, and the latest incidents point to continued heavy fighting, dampening hopes for peace talks.

The Taliban’s main spokesman Zabihullah Mujahid said fighters had overrun checkpoints no more than five km (three miles) from Sar-e Pul city center and seized a large quantity of weapons and equipment.

Amani said fighting was under way on the main highway into neighboring Jawzjan province, at a point around 20 km from the city, while another group of Taliban forces appeared to be gathering in Sheram area, around 3-4 km to the east of the city center.

Security forces, backed by strikes from the Afghan air force, had killed at least 39 Taliban, who had sent in fighters from neighboring provinces to reinforce local forces, he said.

The badly stretched Afghan security forces have suffered tens of thousands of casualties since most international forces ended combat operations in 2014, and the insurgents control large parts of the countryside.

In Jawzjan province, on the northwestern border with Turkemenistan, at least eight members of the security forces were killed in Kham Ab district and 13 wounded. In Samargan province, at least 14 police and civilians were killed in fighting in Dara-e Suf-e Payin district.

In Kunduz province, 15 police were killed and 10 others wounded in attacks on security checkpoints in Dasht-e Archi district overnight, said Amruddin Wali, a member of the local provincial council.