Explosive new claims ramp up pressure on Dilma Rousseff in Brazil

The political crisis engulfing Brazil's president Dilma Rousseff has deepened after her party's former leader in the senate accused her of trying to obstruct the investigation into corruption at state oil giant Petrobras.

As part of a plea-bargain testimony accepted by the country’s supreme court, senator Delcídio do Amaral made a series of explosive claims against the country’s political elite, naming leaders from Ms Rousseff’s ruling Workers Party as well as leading opposition figures as involved in corruption, bribery, obstruction of justice and influence peddling as he painted a disturbing picture for prosecutors of rampant criminality among the top echelons of power in Latin America’s largest country.

Though details of it had leaked in recent weeks the senator's testimony sent shockwaves through Brazil's political class when it was released by the court Tuesday night. He decided to co-operate with prosecutors following his arrest last year after he was recorded arranging to pay an accused Petrobras executive to flee Brazil rather than provide prosecutors with details of wrongdoing inside the company.

In his testimony Mr Amaral claimed he discussed with Ms Rousseff the appointment of a judge to a senior court with the mission to free leading businessmen arrested for their role in the Petrobras investigation before they talked. It is not immediately clear if the senator provided corroborating evidence for the conversation.

Ms Rousseff vehemently denied Mr Amaral’s claims butthe country’s top federal prosecutor said his office “could” now open an investigation into her. It would be the first time during the two-year inquiry into Petrobras that Ms Rousseff, who was energy minister and chairwoman of the company’s board before becoming president, came under formal investigation.

Mr Amaral also provided a recording of a meeting that took place while he was in jail between one of his staff and education minister Aloizio Mercadante, one of Ms Rousseff's closest confidants, in which he appeared to offer her government's help if the senator refused a plea-bargain deal with prosecutors. Mr Mercadante denied he was attempting to obstruct the investigation and said he acted in a personal capacity.

The senator also told investigators it was former Workers Party president Luiz Inácio Lula da Silva who devised the plan to buy the silence of the former Petrobras executive that led to his own arrest.

Among other claims against the former president, whom he cited 186 times in his testimony, Mr Amaral said Lula ordered that the businessman at the centre of the 2005 mensalão congressional vote-buying scandal that almost brought down his government be paid between €25 and €50 million with money stolen from Petrobras for his silence.

Lula, who has already been formally charged with corruption, delayed his plans to accept a ministry in Ms Rousseff’s administration while the implications of the senator’s testimony was digested by the country’s political class.

A consummate political insider who was a member of the opposition before switching to the Workers Party, Mr Amaral also levelled accusations against Ms Rousseff’s estranged vice-president, the heads of the senate and lower house of congress and leaders from the opposition Social Democrats as well as a string of senators and members of congress. They all denied any wrongdoing.