Romney criticises Biden on Benghazi attack

Mitt Romney, Republican candidate for the US presidency, has accused Joe Biden, vice president, of contradicting the testimony of US State Department officials on Libya, in an escalation of the Republican presidential challenger's attacks over the September 11 deaths of four US citizens there.

Hoping to puncture President Barack Obama's credibility on foreign policy ahead of the November 6 election, Romney on Friday jumped on comments that Biden made a day earlier during a debate with Romney's vice presidential running mate, Paul Ryan.

Biden said in his debate with Ryan that "we weren't told they wanted more security" as a row raged over the circumstances surrounding the attack.

Two State Department officials gave sworn testimony on Wednesday at a congressional hearing in Washington saying they had repeatedly requested beefed-up security for the compound before Christopher Stevens, US ambassador, and three other US citizens were killed in the September 11 assault.

Romney told supporters in Richmond, Virginia, on Friday that "when the vice-president of the United States directly contradicts... the sworn testimony of state department officials, American citizens have a right to find out what's going on".

White House spokesman Jay Carney told reporters on Friday that the vice-president was referring only to himself and President Barack Obama when he said "we weren't told".

"Obviously he wasn't talking [about] the administration writ large," Mr Carney said, adding that security matters are handled by the state department.

Biden came out swinging in Thursday's debate, eager to make up for a lacklustre performance by Obama a week earlier against a limber Mr Romney.

Half of uncommitted voters in a CBS poll said Biden had won the encounter, with Mr Ryan receiving 31%. A CNN poll of registered voters said that Ryan was the winner by 4 points.

Romney told Friday's rally in Virginia: "There was one person on stage last night who was thoughtful and respectful and steady and poised, the kind of person you'd want to turn to in a crisis. And that was the next vice-president of the United States, Paul Ryan."

President Obama said he was proud of his 69-year-old running mate's performance in the forum on national security, the economy, taxes and healthcare.

Since their first debate, Romney has erased Obama's lead or pulled ahead of him in nationwide polling.

Obama, however, has managed to maintain his edge, if somewhat diminished, in some of the key swing states that are likely to decide the outcome of the election.

The Democratic president is expected to spend Friday in Washington preparing for his next debate with Romney, a town hall-style format in Hempstead, New York

Their third and last debate is scheduled for 22 October in Boca Raton, Florida.