Republicans call for release of Benghazi email
Republican lawmakers have demanded more information about last year's attack on the US consulate in Benghazi, Libya, a day after new details came to light.
US Secretary of State John Kerry vowed meanwhile to get to the bottom of what happened on 11 September 2012.
On Wednesday a US diplomat said he was "stunned" that UN Ambassador Susan Rice framed the raid as spontaneous, in testimony to a congressional panel.
Four Americans, including Ambassador Christopher Stevens, died in the raid.
House Speaker John Boehner called on the White House to release an email sent by a state department official saying she had informed the Libyan ambassador the attack had been carried out by Islamist militants.
'No stone unturned'
"The state department would not allow our committees to keep copies of this email when it was reviewed," Mr Boehner told reporters on Thursday.
"I would call on the president to order the state department to release this email so the American people can see it."
Meanwhile, Mr Kerry, in Rome, said he had appointed a senior aide, David Wade, to take charge of congressional inquiries relating to the incident.
He pledged he would "leave no stone unturned" to find out what happened during the attack.
Former Secretary of State Hillary Clinton, viewed as a possible 2016 Democratic presidential candidate, angrily defended her handling of the Benghazi raid in a series of hearings on Capitol Hill in January.
On Wednesday, during several hours of emotional testimony, Gregory Hicks, the deputy chief of mission in Tripoli, described in detail how events unfolded on the night of the attack.
He said he was at home watching TV when he received a call from Ambassador Stevens, saying the consulate was under attack. Moments later, the line was cut.
Later that night Mr Hicks heard from the Libyan prime minister, who informed him the ambassador was dead.
During the night, Mr Hicks said he received calls from Libyans using the ambassador's phone. They said they had the envoy with them.
But Mr Hicks did not act on the calls, fearing an ambush.
Mr Hicks also expressed frustration with the lack of a US military response during the night-time attack, saying a second assault could have been deterred.
The Pentagon has said nothing could have been done to assist the Americans in Benghazi.
Meanwhile, UN Ambassador Susan Rice has been heavily criticised for inaccurate comments about the attack in the days immediately afterwards.
She said on a Sunday chat show on 16 September that the attack had grown out of an anti-US protest, while other officials have said they knew at the time it was an organised, armed assault, possibly by an Islamist militant group.
"My jaw dropped and I was embarrassed," Mr Hicks said on his reaction to her interview.
Ambassador Stevens died of smoke inhalation when he was trapped in the burning consulate building, after armed men stormed the compound.
State department employee Sean Smith and former Navy Seals Tyrone Woods and Glen Doherty also died in the attack.
Some Republicans accuse the White House of hiding information about the attack, while Democrats say the issue has become politicised.