Ethiopian Airlines on Tuesday cancelled flights to Bahir Dar, the capital of Amhara, announcing it would not fly to any airports in the region following clashes between local fighters and federal troops.

Last week, the national carrier cancelled flights to three other airports in the northern region.

The escalation in violence in Amhara prompted Prime Minister Abiy Ahmed's government to declare a six-month state of emergency there last week.

"Flights planned for Wednesday, Thursday and Friday to Dessie (Kombolcha), Gondar, Lalibela and Bahir Dar have been cancelled," Ethiopian Airlines said.

The fresh unrest in Africa's second most populous country comes just nine months after the end of a devastating two-year war in the neighbouring region of Tigray.

That war also drew in fighters from Amhara.

Tensions have been rising since April, when the federal government announced it was dismantling regional forces across Ethiopia.

That triggered protests by Amhara nationalists who said the move would weaken their region.

The clashes have prompted travel warnings from foreign governments.

- Gunfire -

Residents of several towns in Amhara told AFP that fighters from the local Fano militia were facing off against federal forces.

Tesfahun, a resident of Bahir Dar, told AFP on Tuesday he had heard artillery fire "non-stop around the airport roads" until midnight on Monday.

"This morning there were gunshots around Lideta 14," a neighbourhood near the airport, he said.

"People are indoors. (There is) no movement."

Simachew, a rickshaw driver in Gondar, told AFP: "Things are really bad here. Aside from gunfire, there is heavy artillery in the city."

"It's really scary even staying indoors because the heavy sounds are just horrific... I don't know how this will end," he added.

The situation in Lalibela, a UNESCO World Heritage site famous for its 12th- and 13th-century rock-cut churches, was "calmer", another resident said.

"We can hear gunshots here and there but it wasn't like yesterday morning," he said.

Fano fighters took over the city and Lalibela airport last week.

The authorities said at the weekend they had arrested people responsible for "the security crisis" in Amhara.

The World Health Organization has said the violence had made humanitarian operations difficult.

The United States has "expressed concern" about the clashes, while Australia, Britain and Spain have advised their citizens against travelling to Amhara.