Brazil has opened a probe into claims linking popular ex-president Luiz Inacio Lula da Silva to a corruption scandal, threatening to cast a shadow over his political legacy and future.

The Public Ministry ordered police Friday to investigate an alleged payoff by Portugal Telecom to the ruling Workers' Party during Lula's first term in office.

Businessman Marcos Valerio Fernandes de Souza has said the former president and ex-finance minister Antonio Palocci negotiated a $7 million payoff in 2005 with the one-time president of a Portuguese phone company through an account in Macau.

Fernandes de Souza received a 40-year sentence last year after he was found to have run much of the scheme that channeled cash to the ruling party.

In December, the high court concluded what was one of the biggest and furthest reaching corruption trials, convicting 25 of 38 people who were accused of corruption including senior ruling party members.

The scandal nearly cost Lula his re-election in 2006. But the 67-year-old founder and leader of the leftist PT was cleared and he has always maintained he was unaware of the scheme. He was not put on trial.

Lula, who had soaring popular approval ratings while in office, was easily re-elected and handed over power to President Dilma Rousseff at the end of his second consecutive four-year term in 2010 as required by the constitution.

[Image via Agence France-Presse]