David Cameron and King Abdullah of Jordan are agreed on the "importance of finding an effective resolution" to the Abu Qatada case, Downing Street has said.

The prime minister told King Abdullah of the "frustrating and difficult" position Britain was in over its efforts to deport the Islamist radical to Jordan.

The UK is unable to return Qatada to Jordan because of a ruling by the European Court of Human Rights (ECHR) that he must not be sent back if it might lead to him being tried with evidence obtained under torture.

An immigration judge ruled earlier this week that Qatada - once described as "Osama bin Laden's right-hand man in Europe" - should be released on bail after more than six years in custody fighting deportation.

Ahead of a visit to Jordanian capital Amman by Home Office minister James Brokenshire next week, Cameron spoke to King Abdullah by telephone this afternoon during a visit to Sweden.

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.

"They both welcomed close and detailed cooperation since the ruling between the Jordanian government, and the UK Home Office and the Foreign Office.

"They agreed on the importance of finding an effective solution to this case, in the interests of both Britain and Jordan."

Qatada, also known as Omar Othman, 51, was convicted in his absence in Jordan of involvement with terror attacks in 1998 and has featured in hate sermons found on videos in the flat of one of the September 11 bombers.

Since 2001, when fears of the domestic terror threat rose in the aftermath of the attacks, he has challenged, and ultimately thwarted, every attempt by the government to detain and deport him.

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".

The ruling was the first time that the Strasbourg-based court has found an extradition would be in violation of Article 6 of the European Convention on Human Rights, the right to a fair trial, which is enshrined in UK law under the Human Rights Act.