US Vice President Joe Biden has had to convince a sceptical Jay Leno that America did not get a raw deal from Russia in the biggest spy swap since the Cold War.

Leno asked Biden during a taping of NBC's "The Tonight Show" why the US was sending 10 accused spies back to Russia while getting only four in return.

"That doesn't seem fair," Leno said.

"We got back four really good ones," Biden reassured Leno. "And the ten, they'd been here a long time, but they hadn't done much."

Leno then showed a sultry photo of alleged Russian agent Anna Chapman and asked "do we have any spies that hot?" The image he showed was taken from a Facebook page and depicts a woman that journalists have identified as Chapman.

Biden's reply, in a mock-serious tone said "let me be clear. It wasn't my idea to send her back."

The spy exchange took place on Friday on airport tarmac in Vienna.

It was Biden's first appearance on the show since taking office in January 2009. Before becoming vice president, Biden had appeared on "The Tonight Show" several times before.