KABUL, May 15 (Xinhua) -- At least six Afghan security forces and eight militants were killed after a heavy fighting broke out in Farah city, provincial capital of western Afghan province of Farah on Tuesday, sources said.

Taliban militants launched a major offensive at around 2:40 a.m. local time Tuesday (2210 GMT Monday) from northern and western neighborhood of the city, in a coordinated effort to seize full control of Farah, a provincial security source told Xinhua anonymously.

"As of now, the initial information said that six security forces were martyred in Farah city," Interior Ministry spokesman Najib Danish told local media Tolo News TV.

"A counter-offensive operation is ongoing and the security forces are trying to bring the situation under control in Farah," he added.

"Our security forces were on high alert before the fighting. There is no fear of collapsing of the city to the hand of insurgents," he said, adding that Special Operations Forces and army commandos together with reinforcement from army have already arrived in Farah.

"The Taliban captured several security checkpoints inside and around the city. Fighting and sporadic clashes are still ongoing at around midday in Police District 3 and western side of the city," the security source told Xinhua earlier by phone.

"The situation is tense. Most people are staying indoors. The streets are deserted. Gunfight, airstrikes and explosions are taking place around the city," he said.

Several security force members, including provincial deputy Police Chief Abdul Razaq, were injured during the fighting, according to Danish.

The province, 695 km west of Afghan capital of Kabul and bordering Iran, has been the scene of heavy clashes between Taliban and security forces over the past few months.

Local military experts believed that the Taliban attacked Farah as they were defeated and failed to take control of southern province of Helmand over the past years.

Taliban militants, who ruled the country before being ousted in late 2001, renewed armed insurgency in recent years. They have intensified armed attacks against security forces across the country since April 25 when the Taliban's so-called yearly rebel offensive started.