Two of the items are 19th-century bark etchings, one belonging to the British Museum, the other to the Royal Botanic Garden at Kew. They have been on show at the Melbourne Museum as part of an exhibition called Etched on Bark 1854, which closed at the end of last month.

An emergency declaration, made under an Aboriginal heritage act, has temporarily stopping the return of the objects, which include a ceremonial emu figure belonging to the British Museum.

The rare etchings were made in the Wimmera region of western Victoria. Their showing in the Etched on Bark exhibition was the first time they had been seen in Australia for 150 years.

The emergency declaration was placed by members of Dja Dja Wurrung and Jupagalk peoples, and represents a mounting discontent among Aborigines at the British Museum and Kew's ownership of the objects.

In May Gary Murray, the chairman of the the North-West Aboriginal Heritage Board, told the Age newspaper in Melbourne: "If the barks go back to England we will be dispossessed a second time."

He told ABC news online: "We've basically put an emergency declaration under the Aboriginal and Torres Strait Islander Heritage Act to stop them from going back."

In a statement, the Melbourne Museum said it had "loan agreements with the British Museum and the Royal Botanic Gardens, Kew, and has obtained import and re-export permits from the Commonwealth government, and is currently seeking legal advice on the impact of the emergency declaration on these agreements and permits".