Downing Street has confirmed that David Cameron has now spoken to King Abdullah of Jordan regarding the release of radical Muslim preacher Abu Qatada.
A spokesman said the Prime Minister and the Jordanian leader agreed on the "importance of finding an effective resolution" as Britain continues to push to have the Islamist cleric deported in order to stand trial in Jordan.
Mr Cameron, who spoke with the King on the telephone from Sweden where he is attending a conference, said Britain had been left in a "frustrating and difficult" position.
The European Court of Human Rights ruled that Abu Qatada must not be sent back to Jordan if his return would mean he is tortured in order to obtain evidence for his trial.
A Downing Street spokesman said: "They discussed the ECHR ruling on Abu Qatada and the Prime Minister explained the frustrating and difficult position that the ruling had created for the UK.
"The Prime Minister complimented the King on the close and effective collaboration between Britain and Jordan on this case over a number of years, and noted that the Court had endorsed the UK-Jordanian MoU (Memorandum of Understanding) on deportation with assurances," he said.
"They both welcomed close and detailed cooperation since the ruling between the Jordanian Government, and the UK Home Office and the Foreign Office."
The spokesman continued: "They agreed on the importance of finding an effective solution to this case, in the interests of both Britain and Jordan."
The Prime Minister said yesterday that the ECHR's decision was "completely unacceptable," following an announcement earlier this week that the radical cleric would be released after six-and-a-half-years in high-security Long Lartin jail, where he has been held without trial as a risk to national security.
Home Office Minister James Brokenshire is to fly to the Jordanian capital Amman next week in a bid to satisfy the ECHR that the Middle Eastern state will not torture Qatada.
Mr Cameron yesterday told MPs that Qatada "should have been deported years ago".
"It is not acceptable that you end up with a situation where you have someone in your country that threatens to do you harm, that you cannot try, you cannot detain and you cannot deport.
"The Government will do everything it can working with our Jordanian friends and allies to make sure that he can be deported," he said.
The 51-year-old preacher, who is also known as Omar Othman, was convicted in his absence in Jordan of involvement with terror attacks in 1998. He also featured in hate sermons in videos found in the home of one of the September 11 bombers.
The ECHR ruled last month that sending Qatada back to face terror charges without assurances about the conduct of a trial would be a "flagrant denial of justice".