Ashlee Simpson has denied reports she has been banned from appearing on hit U.s. TV show Saturday Night Live.

The star was left red-faced after she was caught lip-syncing during a performance on the show in 2004, but reports claim the singer was keen to make a return to the series to promote her new album Bittersweet World.

Sources tell the New York Post's Page Six column Simpson was "a pain" during her time on Saturday Night Live - and that the show's producers were reluctant to have her back.

However, Simpson's publicist insists she won't be appearing on the show due to conflicting schedules.

A representative for the star says, "We're not doing Snl because they're dark (not filming) the week we are here in April and there were no other opportunities later in the year."