Anjem Choudary and a British member of the Isis cell known as The Beatles have been named as “specially designated global terrorists” by the US.
The Department of State said Choudary and El Shafee Elsheikh pose a “significant risk” of terrorism threatening Americans, national security or the country’s economy.
The order imposes sanctions forbidding American nationals from having any dealings with the pair and freezes any of their property or interests subject to US jurisdiction.
Choudary, a 50-year-old hate preacher, was jailed for supporting Isis last year but is feared to be continuing attempts to radicalise and recruit jihadis in prison.
A spokesperson for the US State Department said he acted as a “key figure in Isis’ recruitment drive” and listed his links to convicted terrorists and extremist networks including the proscribed al-Muhajiroun group.
Choudary evaded British law for two decades, despite being linked to a string of terror plots and banned organisations, but was eventually prosecuted after an Isis militant published his declaration of allegiance to the group in 2014.
Elsheikh travelled to Syria in 2012 with friends and joined al-Qaeda’s Syrian branch Jabhat al-Nusra, before defecting to Isis when the groups split.
He has been identified as either “Ringo” or “George” in the British cell known as The Beatles, which including the executioner known as Jihadi John before he was killed in a US drone strike last year.
The group was accused of beheading more than 27 hostages and torturing many more, the State Department said, adding: “Elsheikh was said to have earned a reputation for waterboarding, mock executions, and crucifixions while serving as an Isis jailer.”
His mother, Maha Elgizouli, said the 28-year-old militant was a regular Londoner as a child, but became radicalised after one of his brothers was drawn into gang crime and jailed.
Elsheikh is believed to be living in northern Syria with at least two wives and two children, while his younger brother, Mahmoud, was killed fighting in Iraq.
The other “Beatles” who have been identified include Alexanda Kotey, whose whereabouts are unknown, and Aine Davis, who was arrested in Turkey.
Several British Isis militants have been declared “specially designated global terrorists”, including Scottish jihadi bride Aqsa Mahmood.
The designation has frequently preceded air strikes, such as operations that killed Isis spokesman Abu Muhammad al-Adnani and senior al-Qaeda leaders in Afghanistan.
The Department of State also listed Sami Bouras, a Swedish al-Qaeda member involved in planning suicide attacks, Shane Dominic Crawford, an Isis fighter and propagandist from Trinidad and Tobago, and Mark John Taylor, an Isis militant from New Zealand who used social media to call for terror attacks in his home country and Australia.