Sydney  - Animal rights activists powerless to stop the killing of 400 kangaroos on a Canberra military base Monday appealed to former Beatle Sir Paul McCartney to intercede and save the starving creatures by offering to help pay for their relocation.

"We're not thinking for a moment that Sir Paul should make up all the difference in the cost between whatever Defence feels they are prepared to pay and what it may cost to move them," Canberra Kangaroo Coalition spokesman Mark Drummond told national broadcaster ABC.

The coalition put the cost at shifting the kangaroos at 750,000 Australian dollars (712,000 US dollars) but the Defence Force said many millions of dollars would be needed and many animals would die in the process.

McCartney, a patron of animal welfare lobby group Viva! has condemned plans for the on-again off-again cull.

The 200-hectare site, bounded by five suburbs, has around 600 kangaroos but even at the best of times only enough fodder for 100.

The coalition has pledged to put human shields between sharpshooters and the animals, but activists are being kept away from the 3-metre fence that rings the facility.

After postponing the shoot for a second time in March, a decision was made last week to give up on fertility control and a translocation trial in favour of lethal force.

Michael Linke, the chief executive of animal welfare group RSPCA in Canberra, is backing the decision but is blaming Defence for a decade of neglect that has made the bloodletting unavoidable.

"We're in a situation now where we've got a horrible, horrible disgusting outcome," he said. "They're doing it in the most humane method possible."

Linke noted that kangaroos are not an endangered species and that this year the government has issued permits for the slaughter of 3.6 million. He reckoned up to half the kangaroos would die of stress if the relocation option was pursued and that McCartney and other animal lovers were misguided in their support of it.

"There's a lot of emotion attached to this issue because the kangaroo is one of the iconic native animals, but RSPCA's role is not to be selective about animal welfare," he said. "All the kangaroos would starve to death from a horrible death. It's at an environmental crisis point." (dpa)