By Omar Sobhani
KUNDUZ CITY, Afghanistan (Reuters) - The Afghan army and police on Thursday failed to expel Taliban fighters from the outskirts of a besieged provincial capital as a seventh day of fierce fighting put pressure on national forces struggling largely without U.S. military backup.
The Taliban push is a major test of the Afghan security forces trained by NATO, which ended its combat mission in Afghanistan in December, 13 years after the U.S.-backed military intervention that toppled the hard-line Islamist regime.
The governor of the northern province of Kunduz vowed that the capital, Kunduz city, would not fall to the insurgents, but acknowledged that pushing back the Taliban was proving tough.
"It goes very slowly because we do not want defenseless civilians to suffer," said governor Mohammad Omar Safi.
Four civilians had been wounded, he said, along with 20 Afghan soldiers and police killed and 140 Taliban-allied fighters dead, many of them militants from neighboring Tajikistan and Uzbekistan.
The Taliban, for their part, claimed to have killed 232 Afghan security forces and lost only nine fighters.
Heavy artillery and gunfire rang out on Thursday as government forces fought in two districts on the city's outskirts.
Despite thousands of army reinforcements sent to Kunduz, Taliban fighters held the same positions as several days ago, Mohammad Ali, a local militia commander, complained.
"The government hasn't even made one step forward," Ali said, after visiting two districts just 5 km (3 miles) from the governor's compound.
Dawlat Waziri, a spokesman for the Ministry of Defense, insisted the Afghan national forces had made progress.
"We have the upper hand in this fight," Waziri said.
Kunduz was the insurgents' last stronghold before the U.S.- led forces drove them from power.
A scaled-down NATO mission now mostly trains and advises Afghan forces, although U.S. drones still target militant leaders and an American counter-terrorist force also operates in the country.
The national capital, Kabul, has not seen major violence in the week-old Taliban offensive.
Instead, residents were hit by internet disruptions after a fiber optic cable that supplies Kabul was damaged in the east.
The communications ministry said militants blew up the cable on Wednesday and it would be repaired once security forces arrived to escort engineers to the site.
"At the moment, in Kabul, we are relying on a back-up system that delivers from the north," the deputy minister for IT, Aimal Marjan, told Reuters.
It was unclear if insurgents deliberately targeted the cable. A Taliban spokesman said he was unaware of the incident and declined immediate comment.
(Additional reporting from Kabul by Mirwais Harooni Writing by Kay Johnson; Editing by Clarence Fernandez)