His remarks prompted Ms Riley to reply, saying: "Are you an official Labour spokesperson... or just a big cheerleader?"
The JC understands that, following a meeting of Labour’s national constitutional committee (NCC) who rule on disciplinary cases, Mr James was found guilty of the charges against him and has now been expelled.
Mr James also wrote: “I think Riley is using her influence as a popular celebrity to undermine the Labour party. Her method, though, using her Jewish heritage to promote self-interest, is appalling.’
He added: "Riley has been open about her dislike of Corbyn… You have to hand it to the Tory party for getting her to risk her career for 30 pieces of silver."
Steve Cooke, a member of Stockton North Labour Party and a political education officer, had been instrumental in demanding the party launch an investigation into Mr James' conduct.
It later emerged that Mr James had been subject to an earlier complaint over social media posts in which he said: “Israel is using the Holocaust as an excuse for murder.”
The Labour Against Antisemitism group had sent the Labour complaints team a dossier of Mr James' tweets, together with details of the local party to which he belonged.
But in an email reply sent on February 26, 2018, a Labour complaints officer said the party was unable to identify Mr James as a member and could not therefore take any further action.
Last March, Mr James admitted sending the message to Ms Riley, but denied being antisemitic.
On Monday evening, Mr James said: ”Labour are going down a very dangerous path when people are protected from criticism of their actions or statements because of their race or religion.”
After confirming Mr James had been expelled, a Labour source added: "Under the previous administration, some complaints weren't dealt with adequately.
"Since Jennie Formby became General Secretary, we've used a comprehensive, central complaints system to ensure all complaints are logged and investigated.
"Staff have improved our processes so when a complaint comes in, we can more easily identify whether or not it relates to a member, including identifying people who try to hide behind anonymous social media accounts.
"We have also been conducting audits of historical antisemitism complaints to address past oversights."
