OTTAWA - Embattled International Co-operation Minister Bev Oda is calling it quits July 31 after more than eight years in politics.

Oda - who has come under repeated fire for her champagne spending habits - made the surprise announcement on her website Tuesday, saying in a statement that it's been an "honour and a privilege" to serve her constituents since 2004.

Also in a statement, Prime Minister Stephen Harper thanked Oda, 67, for her time and dedication as an MP and minister and said she informed him of her decision to leave political life two weeks ago.

He also credited her with helping bring more oversight to Canada's aid development budget.

But any accomplishments as minister in charge of helping some of the world's poorest citizens were overshadowed by repeated controversies about her free-spending ways with taxpayer dollars - leading to rampant speculation that Harper was going to boot her from cabinet in the next shuffle.

In April, Oda was forced to apologize and refund the treasury after news broke she upgraded to a room at London's luxurious Savoy Hotel for three nights last year when her original five-star hotel wasn't up to snuff.

During the same trip, she billed taxpayers nearly $1,000 a day for a luxury car and driver and bought a $16 glass of orange juice.

In June, it came to light her staff had combed through five years worth of past travel and hospitality expenses to weed out all inappropriate spending. Oda then cut a cheque to taxpayers for an undisclosed amount.

In 2007, she had to pay back $2,200 after racking up more than $5,000 in limo rides during the 2006 Juno Awards in Halifax.

And while her cabinet colleagues sang Oda's praises Tuesday, taxpayer groups huffed about the golden nest egg she'll soon collect.

"Bev Oda's lifetime pension should cover about 43,841 glasses of $16 orange juice," said Derek Fildebrandt with the Canadian Taxpayers Federation, noting she's entitled to an estimated $701,464 by the time she turns 80.

It wasn't only multiple spending offences that landed Oda in hot water.

Last year she narrowly escaped a charged with contempt of Parliament after admitting to directing a staff member to add the word 'not" to an aid funding memo.

She'd previously denied knowledge of the change.

Oda was first named to the Conservative cabinet in 2006 -- the first Japanese-Canadian cabinet minister in this country's history.