Chuka Umunna has attacked Jeremy Corbyn in a speech at the Liberal Democrat conference, branding him an “apologist for a hard-right Russian government”.
Speaking in Bournemouth, the Labour-turned-Lib-Dem member said leaving the party was one of the “best political decisions" he had made.
He claimed the party was not "liberal" and claimed Mr Corbyn’s supporters would "abuse, vilify and deselect anyone who dares to question the leader”.
“You [Labour] cannot be a champion of liberalism if you are currently subject to a formal investigation by the Equality & Human Right Commission for institutional racism against Jewish people,” he said.
On foreign policy, he said the Labour leader wanted to “abolish NATO” and supported authoritarian regimes in Venezuela and Iran.
Mr Umunna joined the Liberal Democrats in June, after leaving Labour in February to stand as an independent.
To applause, the Lib Dem foreign spokesman added: “I could not be more at home.”
Fellow Labour defector Luciana Berger - who also had a brief stint as an independent before joining the Liberal Democrats - said MPs were being “held hostage” in their parties and she looked forward to more people joining the Liberal Democrats.
“I certainly know there are MPs of all colours that are really struggling with what they see happen and the decisions that are taken by their leaderships,” she said.
Ms Berger said her former home had become “institutionally antisemitic”.