Luiz Inacio "Lula" da Silva, Brazil's former president, has been ordered to stand on trial on charges that he attempted to obstruct a giant corruption probe at Petrobras oil company, according to officials.

The decision published on Friday names Lula, as he is universally known in Brazil, and five others as co-conspirators in an alleged attempt to buy the silence of a former Petrobras director implicated in the scandal.

"The charge is obstruction of justice" linked to the Petrobras oil company embezzlement probe, named Operation Car Wash, a spokesman for the justice ministry told the AFP news agency.

Those charged include former senator Delcidio do Amaral, a former ally in Lula's leftist Workers' Party who is accused of Petrobras-related corruption and has turned state's witness.

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Lula was president from 2003 to 2010 and left office with massive popularity for social programmes, which lifted tens of millions of Brazilians from poverty.

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His legacy, however, has been badly tainted by the emergence of the Petrobras scandal, in which dozens of politicians and executives are accused of having embezzled from the huge state oil company in a bribes-for-contracts network that lasted for much of his presidency.

Brazil's largest engineering companies are accused of overcharging Petrobras for work, and then passing on kickbacks to executives and politicians.

They are also being investigated for graft on venues for the 2014 World Cup and the forthcoming Olympics - events awarded to Brazil under Lula.

"This is the man who brought the Olympics to Brazil," Al Jazeera's Adam Raney, reporting from Rio de Janeiro, said.

"Now, a week before the opening ceremony, it is announced he is going to stand trial - not directly related to this widening corruption scandal, but because he allegedly tried to convince someone to be silent in the investigation."

'Flimsy charges'

Lula has denied any wrongdoing, and his spokesman issued a statement on Friday saying the charges were flimsy.

"The defence argues that the charges are based uniquely on [evidence from] a plea bargain" with Delcidio, the statement said.

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"Lula has never opposed the investigations," it added.

The date of the trial has not yet been set.

The development comes a week before the opening of the Rio Olympics which Lula was instrumental in winning for the city in 2009 while he was still president.

His hand-picked successor Dilma Rousseff faces her own problems, with an impeachment trial set to culminate in late August, days after the end of the Games.

If the Senate votes by a two-thirds majority, she will be removed from office, and her political enemy Michel Temer, who is currently serving as interim president, will take over.

Rousseff is accused of breaking government budgeting rules, but has denounced the impeachment process as a coup in disguise, aimed at putting Temer's centre-right administration in power and destroying the Workers' Party.

Source: Al Jazeera and agencies