A portrait of the Kongouro (Kangaroo) from New Holland, by George Stubbs

A portrait of the Kongouro (Kangaroo) from New Holland, by George Stubbs

A major planned acquisition by the National Gallery has hit a snag, due to a rival claim by the British government.

The claim involves two small paintings by an artist whose work hangs on hundreds of walls across England but it seems the powers that be are loath to part with them.

The gallery confirmed on Tuesday that it had agreed to purchase two paintings by George Stubbs for the Australian national art collection.

A portrait of a large Dog from New Holland (Dingo), by George Stubbs.

A portrait of a large Dog from New Holland (Dingo), by George Stubbs.

But the British government has slapped a temporary export ban on the paintings due to their significance as works relating to England's early explorations of Australia.

The Kongouro from New Holland (of a kangaroo) and a companion painting, A Portrait of a Large Dog from New Holland (of a dingo), pictured, were painted by Stubbs in 1772 after he was commissioned by naturalist Sir Joseph Banks.

Banks had travelled with Captain James Cook on his momentous trip to Australia on the Endeavour in 1768-71, which mapped the east coast of Australia, and it was he who recommended that Australia be colonised, long after Captain Cook's death.

He returned to England with the skin of a large kangaroo and possibly one of a dingo, which were then used by Stubbs, along with skeletons, rough sketches and verbal descriptions, to create the ''portraits''.

The small works have remained in the possession of descendants of the Banks family ever since.

They were first exhibited in the Royal Academy, London in 1773 and were published as engravings as a symbol of Australia in the account of Captain Cook's first voyage to the Pacific.

National Gallery director Ron Radford said the works were relatively modest compared to other works by Stubbs.

The Queen herself owns a large collection, and the artist's works regularly command sums far larger than the estimated £5.5 million - about $8 million - for these two.

But they stand apart as the first significant images of Australia in Europe - not to mention the early prototype for Australia's original coat of arms - and Dr Radford and the family of Joseph Banks believe they belong here in Canberra.

''Even 10 years before we opened, we had them on our wish list as vital things for the National Gallery, but we hadn't been able to get them,'' he said.

''In the last three years, we've been negotiating with the complex family trust which owns them, from the descendants of Joseph Banks' sister.'' The negotiations were successful, with the executors of the trust agreeing Australia was the best place for these relatively modest works.

But the paintings have been stopped in their inevitable trajectory by the British government.

The Reviewing Committee on the Export of Works of Art believes the works should remain in Britain and has imposed the ban to allow time for a British public institution to raise the money to buy them, a process that will last until October.