When she left the Cabinet in 2007, Ms Hewitt said she wanted to spend more time with her family, some of whom live in Australia - where Ms Hewitt was born.
Ms Hewitt was a senior aide to former Labour leader Neil Kinnock and a director of civil liberties organisation Liberty before being elected to Parliament in 1997.
Her decision not to contest the next election cames as Labour MP David Chaytor said he would stand down at the next election after being accused of claiming money for a mortgage he had already paid off.
Transport Secretary Geoff Hoon became the second cabinet minister in 24 hours to repay allowances after he claimed bills in advance for a full year on one property - but claimed a different house was his second home in the same year.
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