Australia has moved to further sanction more than 70 Russian politicians and more than 30 “puppet” Ukrainian government officials installed in the separatist regions of Donetsk and Luhansk.

The move comes as Ukrainian fighters say Russian forces are attacking the encircled Azovstal steel works plant in Mariupol after a ceasefire broke down.

It is believed about 200 civilians remain trapped in bunkers beneath the plant.

Mariupol is a Ukrainian coastal city, south of the Donetsk region in east Ukraine.

Russia recognised the Donetsk and Luhansk regions as independent shortly before its February 24 invasion, leading to international condemnation.

The United States accused Russia of moving to install puppet officials as the Kremlin seeks a “forced capitulation” of Ukraine’s government and to annex much of the country’s east.

US ambassador to the Organisation for Security and Cooperation in Europe Michael Carpenter says Russia is developing plans for a new government and new constitutions to “try to add a veneer of democratic or electoral legitimacy” as it moves to dismantle local governments across Ukraine.

“The reality is that Russia installed puppet regimes dependent on Russian bribes, and orchestrated nebulous ‘people’s councils’ to create phoney constitutions,” he said.

– AAP