0342 GMT May 20, 2018
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 earlier Tuesday from inside Farah.
NATO's Resolute Support mission in Kabul tweeted that the Afghan Army, supported by US airpower including A-10 Thunderbolts, was "on the offensive" and the city "remains under government control".
Interior Ministry spokesman Najib Danish said the Afghan air force was also taking part in the fighting. "(The Taliban) will fail," he vowed.
Defense Ministry spokesman Mohammad Radmanish said at least 10 militants and two Afghan security force members had been killed.
Inside the city residents reported clashes were continuing.
At least some militants have been hiding in private houses, making it difficult for Afghan forces to use heavy weapons, Farah Governor Abdul Basir Salangi told Ariana News, adding: "But still we are taking back positions one by one."
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, a project with which the Taliban have pledged to cooperate.
But it has been the scene of intense fighting in recent years. In 2017 militants tried three times to overrun the capital, according to the Afghanistan Analysts Network.
As such, Tuesday's offensive "should not have taken government forces off guard", said military analyst and retired general Atiqullah Amarkhail.
Afghan troops and police nationwide have struggled to hold back the resurgent Taliban since the withdrawal of most NATO combat forces at the end of 2014.
The militants have tried several times to take provincial capitals in recent years, including Kunduz and Lashkar Gah, with the Afghan army deploying significant numbers of troops to hold those cities and push the militants out.
Kunduz, Afghanistan's fifth largest city and capital of the northern province of the same name, fell briefly to the Taliban in 2015.