The US did not inform the Libyan government about the arrest of the suspected ringleader of the 2012 on an American diplomatic compound, according to a Libyan minister.
The US Ambassador to the United Nations, Samantha Power, notified the UN Security Council of the capture on Sunday of Ahmed Abu Khatallah by US special forces.
She said an investigation had not only implicated him in the 2012 raid but also planned "further armed attacks" against US personnel.
More top news
You can't say the 130 Brexit Tory MPs who forced Cameron to have this referendum haven't had an impact on political life, writes Chris Ship.
Foreign Secretary Philip Hammond said there will have to be a "trade-off" on access to the EU single market and migration controls.
A man arrested on suspicion of murdering Melanie Hall 20 years ago has been released on police bail. She disappeared in Bath in 1996.