Provincial governor Basir Salangi said that Taliban attacked Farah city around 2am local time and suffered heavy casualties.
Qari Yousuf Ahmadi, a spokesman for Taliban said large scale attacks will continue in Farah and he warned civilians to remain inside their houses. He said fighters launched attacks form multiple directions, after which they overran several checkpoints in the city.
Local military experts believed the Taliban offensive followed their loss of control over the southern province of Helmand.
"The Afghan National Defense and Security forces supported by USA forces in Afghanistan air power are on the offensive against the Taliban", he added.
The assault comes as the Taliban are stepping up their spring offensive, in an apparent rejection of a peace talks overture by the Afghan government. "Gun battles, air strikes and explosions are taking place around the city", he told Xinhua earlier by phone.
A resurgent Taliban, largely dependent on narcotics revenues, has expanded its territorial control over parts of Afghanistan since the withdrawal of most worldwide combat forces at the end of 2014.
Danish at a joint press conference with the Ministry of Defence (MoD) Mohammad Radmanish said that security forces from southern Kandahar and western Herat provinces have been deployed to the province to "eliminate the threats". Another provincial council member, Dadullah Qani, confirmed Hissaini's comments, the sound of gunfire and explosions audible as he spoke to an AFP reporter by telephone.
"An intense battle is going on in the city", he said without providing additional details.
Many radio and television channels in the province have stopped broadcasting, fearing for their employees' lives, according to media watchdog Nai.
Most have been in capital city Kabul, but in January gunmen attacked an office of aid group Save the Children in Jalalabad, killing at least five people and wounding 25.
The Taliban have pledged to cooperate with the project.