Macovei, 55, on Tuesday resigned from the opposition Liberal Democrat Party, PDL, and announced that she will run as an independent candidate in November’s presidential elections.

Currently a Member of the European Parliament, she is best known for pushing through key reforms to the judiciary and for cracking down on corruption when she was Justice Minister between 2004 and 2007.

“I’ve decided to leave the PDL as the party’s candidate for the presidential elections is not really promoting the rule of law and an anti-corruption drive,” Macovei said in a public statement.

“So, I have decided to run as an independent. It hasn’t been an easy choice, but it is a challenge I assume with determination and faith,” she added.

The PDL and the centre-right National Liberal Party, PNL, are running a joint candidate in the presidential elections, Klaus Iohannis, 55, mayor of the Transylvanian city of Sibiu.

Macovei is the second woman to enter the presidential race. Last month, Elena Udrea, leader of the Popular Movement Party, PMP, and a close ally of outgoing president Traian Basescu, launched her candidacy.

Neither woman stands much of a chance against the current front runner, the Prime Minister and leader of the governing Social Democrats, Victor Ponta.

A recent poll suggested that Ponta would get 46 per cent of the votes in the first round on November 2, well ahead of the likely runner up, Iohannis, who is tipped to come second with around 24 per cent.

Polls suggest that the independent candidates will get only around 6 per cent of the votes.

A trained lawyer who spent most of her career defending human rights, Macovei was made justice minister in December 2004, when Romania urgently needed to show Brussels that it was serious about fighting corruption.

While winning strong support in the European Commission and among the public, she was deeply unpopular among legislators who feared her campaign.

She was fired in 2007, her removal being precipitated by the rupture in the then governing coalition. In 2009 she was elected to the European Parliament.