British Prime Minister David Cameron and his main election rival Ed Miliband have faced a prime time television grilling, kicking off a tight race for the May 7 election.

A snap Guardian/ICM poll of viewers said 54 percent believed Cameron of the Conservatives had put in the strongest performance compared to 46 percent for Labour leader Miliband.

The two politicians were questioned separately and had no exchanges, after months of wrangling over the format failed to deliver a head-to-head debate between them.

Commentators say Cameron's Conservatives did not want one in the belief that a lacklustre performance in TV debates during the 2010 election campaign contributed to their failure to win outright.

Both leaders faced tough questioning by veteran interviewer Jeremy Paxman - known for his withering glares and quizzical raised eyebrows - which left Cameron looking uncomfortable, while Miliband took a more combative approach in response.

When asked if he was up to the job of being prime minister, Miliband, who has struggled with a geeky media image, hit back: "Am I tough enough? Hell yes, I'm tough enough."

Cameron, meanwhile, was questioned about where austerity cuts would fall, his plans to hold a referendum on Britain leaving the European Union and his disclosure this week that he would not stand for a third term.

"You are going to have to make this huge choice in 42 days' time," he said.

"What I have learnt in the last five years is that nothing you want to do will work without a strong and growing economy."

The two leaders also faced questions from members of the public in the studio audience.

The Conservatives and Labour are currently neck-and-neck in the polls on 34 percent, according to an average calculated by the UK Polling Report website.