Updated

Former president Nicolas Sarkozy on Thursday resigned from France's top constitutional body after it upheld a decision that he had breached official spending limits during last year's election campaign.

After a decision that threatened to throw the main opposition UMP -- already reeling from a leadership battle -- into further chaos, Sarkozy said in a statement to AFP that he was resigning "immediately" from the Constitutional Council.

This was to "regain his freedom on speech" to react to the decision, which sees him lose out on a 10 million euro ($13 million) reimbursement.

The Council, the country's top constitutional authority, said in a statement that it was confirming a decision by France's electoral finance watchdog that Sarkozy had filed expenses of nearly 23 million euros, which exceeded the spending ceiling by 2.1 percent.

Because of this Sarkozy, who lost to Socialist Francois Hollande in the vote, is not eligible for the reimbursement of 47.5 percent of total campaign spending he was due under election financing laws.

Sarkozy will also need to return 150,000 euros advanced by the state for the campaign.

The former president has been implicated in a series of campaign funding scandals allegedly involving Liliane Bettencourt, France's richest woman, and former Libyan dictator Moamer Kadhafi. Sarkozy has denied any wrongdoing.

Former presidents are automatically appointed to the body.