Downing Street was given a report on the foreign funding of UK extremism last year - but Theresa May still hasn't decided whether to publish it.
The report, thought to focus on Saudi Arabia, was commissioned by David Cameron and then approved by May, as part of a deal with the Lib Dems to ensure the Tories had support before a vote on Syrian airstrikes in December 2015.
Home secretary Amber Rudd and Foreign Secretary Boris Johnson have both suggested the findings may never be released - even though outgoing Lib Dem leader Tim Farron has claimed this was a key condition of the initial pact.
Now Caroline Lucas, co-leader of the Green Party, has raised the issue, urging the Prime Minister to release the report's findings.
Lucas implored May "to reveal immediately whose advice they are following as to whether or not to publish this report, and to do all they can to put the facts into the public domain if it is safe to do so.”
She said the decision to hold back the report "leaves question marks over whether [the Government's] decision is influenced by our diplomatic ties.
“The Government is sitting on this report but refusing to publish it or give any reason for their continued secrecy. To defeat terror, it’s vital that politicians have full view of the facts, even if they are inconvenient for the Government."
The Guardian reports that the Home Office and Downing Street have responded to the concerns raised by Lucas, saying that the decision on whether to publicise the report is down to the Prime Minister.
Theresa May has herself said ministers are “considering advice on what is able to be published and will report to parliament with an update in due course.”