Myanmar pro-democracy fighters in a battered pickup truck drive past abandoned and bombed-out houses in the eastern city of Loikaw, on their way to the front lines of the battle to capture their first state capital from the junta.

"Our soldiers are from Loikaw township and it's the main reason we are motivated. We all are doing our best with the hope of going back to our homes," Lin Lin, their leader, said.

He belongs to one of the dozens of "People's Defense Force" groups that sprung up across Myanmar to fight the military's 2021 coup and are now determined to capture Loikaw and deal a blow to the country's rulers.

PDFs and allied ethnic minority groups have been battling the Myanmar army for weeks in and around Loikaw, a city nestled in lush hills and home to around 50,000 people in eastern Kayah state.

Thousands of residents have already fled air attacks, artillery bombardments and urban battles, PDF fighters said.

Earlier this week, the streets were silent apart from the sounds of sporadic artillery fire.

"At the moment the military is on the defensive," Lin Lin said.

The junta is reeling from an offensive by three ethnic minority groups along the rugged northern border with China that has captured several towns and blocked vital trade routes.

This offensive, dubbed "Operation 1027" after the date it was launched five weeks ago, is the biggest challenge faced by Myanmar's army since it seized power.

Soon after clashes erupted in northern Shan state, other PDF groups opened new fronts in several other states, including Kayah.

Inside Loikaw, footage obtained by Agence France-Presse shows abandoned houses and shops and streets pockmarked by explosions.

Buildings have been damaged by artillery shells and on some street corners positions fortified with sandbags can be seen.

The military was holed up in the city police station and other buildings, Khun Bedu, the chairman of the Karenni Nationalities Defense Force, one of the groups fighting in Loikaw, told AFP.

With ground troops pinned down, the military was relying on its air and artillery strikes to support its troops, Khun Bedu said.

The military "called in airstrikes on us in many places in the town last night," he told AFP on Friday. "We will continue to fight."

The KNDF posted footage two weeks ago that it said showed its fighters receiving the surrender of junta troops who had been holed up in the city's university.