A group of Welsh Labour members has called for Jeremy Corbyn’s suspension from the party “to be dropped immediately”.
The former leader was suspended for saying the scale of anti-Semitism in Labour was “dramatically overstated”.
The comments followed a highly critical report by a human rights watchdog.
But Welsh Labour Grassroots, the Welsh equivalent of the Momentum group, said Mr Corbyn’s statement “contains nothing that would justify” his suspension.
In a statement, the group on the left of the Welsh party said: “As always, he was unequivocal about the unacceptability of anti-Semitic views and behaviour, and about the need for Labour to rebuild trust with Jewish communities.
“The grounds for Jeremy’s suspension have not yet been made clear and, moreover, the legitimacy of the process by which the decision was made appears questionable,” it said.
The group said the suspension was an “unwarranted attack on those many thousands of Labour Party members who were and remain inspired by Jeremy’s socialist vision and principles, who now feel let down by the leadership’s action”.
It called on members to “remain in the Labour Party” rather than leave in protest.
Wales’ First Minister Mark Drakeford has refused to comment on the suspension of Mr Corbyn, who he had backed in Labour leadership campaigns.
Asked on Friday whether he regretted, in hindsight, supporting Mr Corbyn, the Welsh Labour leader replied: “On page 49 the report criticises the previous leadership for interfering or attempting to influence formal procedures and it says it is not legitimate for the leadership to influence formal complaints procedures.
“There is a formal process in train and I am not going to comment on it because the report I have welcomed expressly tells me not to.”
But Mr Drakeford added that anti-Semitism “has no place at all in the Labour Party or in Welsh society” and that “anti-Semitism is a stain on any society and it has been a stain on the reputation of the Labour Party”.
Shadow Welsh Secretary Nia Griffith said the suspension was “absolutely right” because Mr Corbyn “was asked to rethink the words that he used and he decided not to”.
The Equality and Human Rights Commission report found Labour had been responsible for three breaches of the Equality Act:
The commission found evidence of 23 instances of “inappropriate involvement” by Mr Corbyn’s office.