The Member for Shellharbour, on the New South Wales south coast, is the latest Labor MP to say they will not contest the next state election.

Lylea McMahon has announced she will stand down before next year's state election.

Earlier this week Western Sydney MP Tanya Gadiel said she would be retiring from politics.

Ms McMahon is the 20th Labor MP who has announced they are bowing out of politics.

But that figure does not include the MP for Drummoyne Angela D'Amore who has been stripped of her Labor Party membership after an adverse corruption finding.