A group of London Assembly candidates and council leaders have called on Labour’s general secretary to expel Ken Livingstone.

The former mayoral of London was suspended for bringing the party into disrepute last Thursday after claiming Hitler was a Zionist – and repeatedly refused to say sorry for hurt to the Jewish community.

Andrew Dismore, Labour’s candidate for Barnet and Camden in Thursday’s London Assembly elections, has written to the party’s general secretary saying the “unambiguously anti-Semitic” remarks had caused “profound anguish and concern”.

While arguing the party “was starting to get a grip” following a string of suspensions of party members, councillors and an MP, he argued: “We must deal with that small number of unreformable recalcitrants like Ken Livingstone, who I believe must part company with us for good.

“He has form and is a serial offender. His inability to recognise this or apologise for his crass and offensive outbursts and actions now, a Mayor, or at previous London elections, has damaged our standing, and we must now grasp the nettle and take action. If Ken cannot be persuaded to leave voluntarily for the good of the party, he should be chucked out – and the NEC must see to this with speed and resolve.”

The letter is supported by eight Assembly candidates including Mike Katz, Navin Shah and Alison Moore as well as the leaders of Camden and Ealing councils and the head of then Labour group on Barnet council.

Dismore – who said the party had through its history championed Jewish rights in the UK and introduced Holocaust Memorial Day following a campaign he introduced – said it would be a “tragedy if he were to be unfairly stigmatised due to Livingstone and those of his ilk” after he had campaigned extensively within the community.

Ahead of Yom HaShoah, he added: “Let us make our contribution to the memory of the victims of this terrible crime by taking the firmest possible action against all who dare to espouse the world’s longest hate.”