(Reuters) - Hundreds of Taliban fighters have stormed a strategic district in an Afghan province not far from the capital, killing dozens of people in five days of fighting and the insurgents could capture the area, officials said on Friday.

The Ghazni provincial government has lost contact with police in the province's western district of Ajrestan, said Asadullah Safi, deputy police chief of the area.

Ghazni, is southwest of the capital, Kabul, and a key link to the south and southeast, where the Taliban have been making advances in recent months.

"If there is no urgent help from the central government, the district will collapse," Safi said.

The battle for Ajrestan illustrates the grave challenges facing Afghanistan's new president and the security forces in holding territory as foreign combat troops prepare to leave at the end of the year.

Control of Ajrestan, about 200 km (125 miles) from Kabul, would provide the Taliban with a launching point for attacks into adjacent Uruzgan and Daikundi provinces.

Heavy fighting was going on in Ajrestan on Friday. Safi said a suicide car bomber attacked a police checkpoint early in the day before provincial authorities completely lost contact with the district.

The attack by an estimated 700 Taliban fighters began about five days ago and early reports were that more than 100 people had been killed, including 15 who were beheaded by the militants, said provincial deputy governor Ahmadullah Ahmadi.

Provincial authorities have appealed for help from the central government in Kabul, where President-elect Ashraf Ghani is in the process of taking over from Hamid Karzai.

"We have asked repeatedly for helicopters to evacuate the wounded, but so far nothing has been done," Ahmadi said.

However, a regional spokesman for the Afghan army, Nazif Sultani, said on Friday reinforcements had been sent to the district the previous day. He said he had no further information.

(Reporting by Mustafa Andalib in Ghazni and Mirwaid Harooni in Kabul; Editing by Kay Johnson and Robert Birsel)