A former FBI agent has made new claims that 1960s pop star Sonny Bono was assassinated.

Ted Gunderson said that Cher's former husband was targeted in a politically-motivated assassination in January 1998.

However, Bono's autopsy concluded that he died of injuries sustained after crashing into a tree while skiing at the Heavenly Ski Resort in Nevada.

"It's nonsense for anyone to now try to suggest that Bono died after crashing into a tree," Gunderson told America's Globe.

"There's zero evidence in this autopsy report to show such an accident happened. Instead, there's powerful proof he was assassinated.

"This was an evil plot that was carried out to almost perfection by ruthless assassins."

Gunderson said hitmen hired by top US officials moved in on him because Bono - a member of the US House Of Representatives - was believed to be about to expose an international drug and weapons ring.

His claims are reportedly backed by several top forensic experts.