Bill Cosby goes on the defensive.

The comedian declined to answer questions by a National Public Radio (NPR) journalist about accusations of sexual assault that resurfaced in recent weeks.

Cosby responded by shaking his head "No" at least twice when asked to comment on the claims which date back to the 80s.

The 77-year-old has never been charged with the alleged crimes.

The allegations resurfaced in October when a comedian called Cosby a "rapist" during a stand-up routine.

Cosby is currently developing a new sitcom for U.S. network NBC.