American Idol judge Paula Abdul has fiercely denied she was drunk when she made an embarrassing blunder on the hit reality TV show on Tuesday.

The singer was blasted by American gossip website TMZ.com, which accused the singer of being under the influence of alcohol when she was caught out by a change to the judging format of the show.

When asked to appraise first performer Jason Castro, Abdul gave her opinions on two performances - even though each singer had only sung once.

The website had claimed she was "bubbly" after "at least one martini" at a lunch at Maggiano’s restaurant in Los Angeles four hours before the show began.

But Abdul brands the claims "absolutely not true" saying, "It got very confusing. The producers come up to us in the dark and said, ‘We are not going to have you guys judge after each performer, we are going to have all the performers go once, then twice and at the end critique them.’"