A legal letter from Taylor Swift's lawyers has allegedly surfaced showing she did approve of Kanye West's song Famous.

Kanye debuted the song, in which he jokes about sleeping with Taylor and calls her a b**ch, during an album launch and fashion show event in New York earlier this year (16), prompting Swift's representative to blast his choice of lyrics.

Kanye shot back and revealed Taylor was aware of the song and had given him the OK to reference her, but the pop star's reps insisted that was not the case.

Then, in a GQ interview last week (ends17Jun16), Kanye's wife Kim Kardashian alleged Taylor "totally knew" about the song, and that a tape of the phone call in which she agreed to the track being released exists.

Britain's The Sun newspaper now claims it has seen a legal letter sent by Taylor's lawyers, in which they are said to demand that the tape of the conversation should be destroyed.

"Taylor got her lawyers to threaten Kanye and demanded that the recording was killed," a source told the newspaper. "They stressed the phone call was confidential and that publishing it would violate her rights.

"It validates that a taped conversation where Taylor was on board with the song does exist, and just shows how worried she is about the truth coming out."

Following Kim's chat with GQ, Taylor's representatives released a statement in which they accused the reality star of being "incorrect" in her claims.

However, they did say in a statement: "Taylor has never denied that conversation took place. It was on that phone call that Kanye West also asked her to release the song on her Twitter account, which she declined to do. Kanye West never told Taylor he was going to use the term 'that b**ch' in referencing her. A song cannot be approved if it was never heard.

"Kanye West never played the song for Taylor Swift. Taylor heard it for the first time when everyone else did and was humiliated.... Taylor cannot understand why Kanye West, and now Kim Kardashian, will not just leave her alone."