Australia’s foreign minister, Marise Payne, raised the case of the WikiLeaks co-founder Julian Assange with the US secretary of state during her visit to Washington DC this month, the government has revealed.

But Australian parliamentarians who support Assange say the government should demand his immediate release, after a US news report this week claimed CIA officials during the Trump administration had discussed abducting and even assassinating the Australian citizen.

Assange remains in Belmarsh prison in London as the US government appeals against an earlier court ruling that blocked his extradition to face charges, including allegedly obtaining and publishing classified documents in violation of the US Espionage Act.