An Aboriginal delegation in London seeking the return of Aboriginal human remains in British museums, says it will sue the British Natural History Museum, if it refuses to return Indigenous body parts in its collection.

Although this week both London's Horniman Museum and Manchester Museum handed back Aboriginal body parts in their possession others, like Natural History Museum, says its collection should stay in Britain in the interests of scientific research.

"(You) can't argue about the right of these remains to come home and rest in the place where they belong. This is not about ownership. This is about the right of the people, that the remains of these people come home," said Aboriginal and Torres Strait Islander Commissioner, Rodney Dillon.

It is estimated there are thousands of Aboriginal body parts still held in British institutions despite an agreement between the governments of both countries to encourage their repatriation.