LONDON: British Prime Minister David Cameron on Thursday ruled out banning Egypt's Muslim Brotherhood but said the group had a “highly ambiguous relationship with violent extremism” and was “opaque” and “secretive”.

Membership or having links to the Islamist organisation, which is an opposition force in Egypt and has a base in London, should be considered a “possible indicator of extremism,” Cameron said.

His written statement contained the main findings of a review into the Muslim Brotherhood's activities whose publication has been delayed for months.

Britain has come under pressure from countries like Egypt and Saudi Arabia to ban the Muslim Brotherhood, and ministers had been accused of delaying the review so as not to upset allies in the Middle East.

Egypt has cracked down on the Islamist group since its leader Mohammed Morsi was ousted as president by the military in 2013, with thousands of supporters arrested and hundreds condemned to death in mass trials.

Cameron said the government would “keep under review whether the views and activities of the Muslim Brotherhood meet the legal test for proscription”.

“Parts of the Muslim Brotherhood have a highly ambiguous relationship with violent extremism,” he said, describing the group as “deliberately opaque and habitually secretive”.

“Both as an ideology and as a network it has been a rite of passage for some individuals and groups who have gone on to engage in violence and terrorism.”

The Brotherhood's British lawyers could not immediately be reached for comment.