MP Ivan Lewis has resigned his Labour Party membership, a year after he was suspended over sexual harassment claims.
Mr Lewis, who sits as an independent, quit with an attack on Jeremy Corbyn's handling of the anti-Semitism row.
He has also claimed there had been an "unnecessary and politically motivated delay" in dealing with his case.
Labour said it took sexual harassment investigations seriously and the process was "the same for everyone".
Throughout the summer Labour was beset by arguments over its handling of the long-running anti-Semitism row.
In his resignation letter, the Bury South MP, who was a minister in the governments of Tony Blair and Gordon Brown, accused Mr Corbyn of being "unwilling to condemn those whose hatred of Israel becomes Jew hatred", saying this was "incompatible with being a lifelong campaigner against racism".
Mr Corbyn has repeatedly apologised for the hurt caused to Jewish people by the anti-Semitism in his party and vowed to do more to root it out.
Apology to women
Mr Lewis was suspended from the party in November 2017, following allegations, reported by Buzzfeed News, that he had touched a woman's leg and invited her to his house at a Labour Party event in 2010.
He has denied sexually harassing anyone but has said he was sorry if his behaviour towards women he worked with had made anyone feel "awkward".
He has also complained that he was suspended "despite never having been interviewed about complaints which have been made against me".
A Labour Party spokesman said: "Jeremy Corbyn thanks Ivan for his service to the Labour Party.
"The Labour Party takes all complaints of sexual harassment extremely seriously, which are fully investigated in line with our rules and procedures and appropriate disciplinary action taken.
"This case was referred to a full hearing of Labour's National Constitutional Committee. The process is the same for everyone."