A group of U.K. lawmakers went to Washington this week to press the U.S. government to release the last Briton held at Guantanamo Bay.
The delegation was made up of David Davis and Andrew Mitchell, two MPs from the ruling Conservative party, and Andy Slaughter and Jeremy Corbyn, two MPs from the opposition Labour party.
They met U.S. senators including John McCain, as well as Defense and State Department officials.
Shaker Aamer, a 48-year-old British resident, has been detained at Guantanamo Bay since 2002 without charge or trial.
The British government has long campaigned for the release of Aamer, a Saudi national who lives in London. He has a British wife and four British children.
Prime Minister David Cameron raised the subject in a meeting with President Barack Obama in January, the Guardian reported at the time, and the U.K's parliament voted unanimously in March to press for Aamer's release.
Slaughter described the meetings as "positive" in a statement, but a Wall Street Journal report on the trip quoted State and Defense department spokespeople who did not commit to a specific timeframe for when Aamer might be released.
Aamer was cleared for release in 2007, but only on the condition that he moved to Saudi Arabia, Mitchell said in an interview on Wednesday with Sky News. Aamer has been beaten and put in solitary confinement for long spells during his time at Guantanamo, his lawyers say.