Brazil Speaker Eduardo Cunha facing corruption charges

Mr Cunha is one of the government's most outspoken opponents in Congress

Brazilian prosecutors investigating a major corruption scandal have filed charges against the speaker of the lower house of Congress, Eduardo Cunha.

He is accused of taking $5m (£3.2m) in bribes to secure contracts with the state oil giant, Petrobras.

Mr Cunha denies the allegations and says they are politically motivated. He is an outspoken critic of President Dilma Rousseff.

Charges have been submitted against ex-President Fernando Collor de Mello.

Mr Collor de Mello was in power between 1990 and 1992, when he resigned hours before the Senate was due to vote on his impeachment for corruption.

Brazil's Attorney General, Rodrigo Janot, has accused Mr Cunha of corruption and money laundering.

The charges against Mr Collor de Mello have not been disclosed.

He was on a previous list of people under investigation over the Petrobras corruption scandal. He has also denied any wrongdoing.

Mr Collor de Mello was the first president elected after democracy was restored in Brazil in 1989

Mr Collor de Mello's office has posted a message on Facebook accusing the attorney general of "playing for the media".

"Everything could have been clarified had the senator been given the right to examine the accusations and offer his explanations," reads the post.

Mr Collor de Mello says he is "the main victim of this plot".

The Supreme Court will now have to decide whether to accept the charges.

As congressmen, both men would be tried by the Supreme Court.

'Not standing down'

Mr Cunha said earlier this week that he would remain in his post as Speaker of the Chamber of Deputies even if he was indicted.

"I am not going to stand down in any way. I am going to carrying on doing the job I was elected to to by the majority of the House," he said.

Dozens of politicians, businessmen and civil servants have been charged over the past year in connection with the Petrobras scandal.

"In defence of democracy, stay Dilma," reads the banner at a pro-government demonstration in Sao Paulo

Hundreds of thousands of demonstrators called for Ms Rousseff's impeachment on Sunday in marches across the country

The corruption allegations and Brazil's economic crisis have helped push Ms Rousseff's popularity to record low figures.

She was head of Petrobras for several years but has not been implicated in the scandal.

Last month, Mr Cunha left the biggest party in the governing coalition, PMDB, in order to join a campaign calling for Ms Rousseff's impeachment.

Ms Rousseff, from the left-wing Workers Party, was re-elected in October to a second four-year term.

Her supporters say calls for her impeachment amount to a coup attempt by right-wing politicians defeated in last year's polls.

Mass pro-government demonstrations were held across the country on Thursday evening.