The Bar Standards Board (BSB) has issued an immediate suspension order preventing barrister Michael Shrimpton from practising.
Mr Shrimpton was convicted of communicating false information at Southwark Crown Court last week. He is reported to have called the former defence secretary in 2012 claiming to have intelligence about a terrorist bomb attack at the London Olympics.
Mr Shrimpton is said to have left a message for Philip Hammond, and spoken to his private secretary, telling them that a stolen Russian nuclear warhead would be used to attack either the Olympic Stadium or the Queen, as she attended the opening ceremony.
He will be sentenced next year after being sent for psychiatrict assessment.
The BSB said it was aware of court proceedings involving Mr Shrimpton “in relation to a bomb hoax” and had started professional misconduct proceedings against him as a result.
The regulator said that following his conviction last week and “considering also his previous conviction for the possession of indecent images of children”, an immediate suspension order had been issued.
“The continuation of this suspension and any final disciplinary action will be considered in due course, in accordance with the BSB’s usual disciplinary procedures,” a spokesman said.
“Action had already been taken by the BSB in relation to Mr Shrimpton’s previous conviction for the possession of indecent images of children and his ability to practise as a barrister.
“In April 2013, when we became aware of the charges which led to his first conviction, we immediately acted to restrict Mr Shrimpton’s professional capacity.
“We required Mr Shrimpton to declare all of the charges against him to his clients, before representing them. Following his conviction under the Protection of Children Act in February 2014 we also prevented him from being involved in any cases concerning the welfare of a child, allegations of sexual abuse or impropriety concerning a child or where a child was liable to be a witness.”