6:02pm UK, Friday February 13, 2004

The man hoping to take on George Bush for the US presidency has denied allegations of an affair with an intern.

Democrat frontrunner John Kerry said he was "a fighter" - and that was how he would approach any smear stories.

Kerry With Wife Teresa

Asked on TV if he was concerned about the rumours, SenatorKerry replied: "Well, there is nothing to report, so there is nothing to talk about.

"I'm not worried about it, the answer is no."

Mr Kerry has won 12 of the 14 states to have so far voted in the selection process, easily outstripping the early favourite Howard Dean.

He said he was expecting a Republican onslaught as his momentum grew stronger.

"And I think we've seen the evidence. We know exactly where they're going to go."

Political observers in the US say Republicans are more afraid of Mr Kerry winning the Democrat nomination than Mr Dean.

Mr Kerry is a much-decorated war hero while Mr Bush has faced allegations of draft dodging.