The attack the first major assault targeting a city since the Taliban launched their annual spring offensive -- began around midnight, with the militants capturing one urban district and parts of another, said local provincial council member Jamila Amini.
"Heavy fighting continues inside the city and aircraft have just started bombarding Taliban positions," she told AFP Tuesday from inside Farah.
At least 23 killed in multiple attacks in Afghanistan
Afghan officials said police special forces from Kandahar and commandos from Herat had also been deployed.
"(The Taliban) will fail," vowed interior ministry spokesperson Najib Danish, who said both Afghan and foreign air forces were taking part in the fighting.
There was no immediate confirmation from NATO's mission in Kabul.
At least nine dead as bomb, gun battle rages in Afghan city
Defence ministry spokesperson Mohammad Radmnish said at least 10 insurgents and two Afghan security force members had been killed so far.
"The situation is under control and will change by the end of the day," he said.
But inside the city residents reported clashes were continuing. "The situation is very bad," Satar Hissaini, a tribal elder in Farah, told AFP.
"Heavy fighting is going on and Taliban are in the city but the police headquarters and NDS (the Afghan intelligence agency) have not fallen to them," he said.
"NDS forces in their HQ are engaged in heavy clashes with the Taliban."
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.
The noise has 'filled the city', said one resident who gave his name as Bilal, adding that he could see smoke rising from the direction of a building housing the NDS.
The insurgents released a statement warning residents to stay inside their homes and 'stay calm'.
Many radio and television channels in the province have stopped broadcasting, fearing for their employees' lives, according to media watchdog Nai.
The Taliban are stepping up their spring offensive, in an apparent rejection of a peace talks overture from the government.
Farah is a poppy-growing province in an isolated region of Afghanistan.
There are plans for a section of the multi-billion-dollar TAPI (Turkmenistan, Afghanistan, Pakistan and India) gas pipeline to traverse it.
Despite security concerns, the Taliban have pledged to cooperate with the gas project.
Afghan peace: ‘Suicide attacks violate Islamic principles’
Farah, which borders Iran, has been the scene of intense fighting in recent years. In 2017 insurgents tried three times to overrun the capital, according to the Afghanistan Analysts Network.
Afghan troops and police nationwide have struggled to hold back the resurgent Taliban since the withdrawal of NATO combat forces at the end of 2014.
The insurgents have tried several times to take provincial capitals in recent years, including Kunduz and Lashkar Gah.
Kunduz, Afghanistan's fifth largest city and capital of the northern province of the same name, fell briefly to the Taliban in 2015.
They along with the Islamic State group have also stepped up their attacks in the capital Kabul, which the UN says has in recent years become one of the country's deadliest places for civilians.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ