(Adds background on investigations, statement from Odebrecht)
GENEVA, July 22 (Reuters) - The Swiss Attorney General's office said on Wednesday it has widened a corruption investigation into Brazilian oil firm Petrobras to include Latin America's largest engineering and construction company, Odebrecht SA, and its subsidiaries.
Swiss authorities have been collaborating with Brazil on the Petrobras probe since at least March. Their help with an ongoing Brazilian investigation of Odebrecht, however, could be key in tracking bribes allegedly paid to former Petrobras executives.
"Subsidiaries of Odebrecht are suspected of using Swiss accounts to make bribery payments to former Petrobras executives, who also maintained Swiss bank accounts," the Attorney General's office said in a statement.
Marcelo Odebrecht, chief executive of Brazil-based Odebrecht SA, was arrested in Sao Paulo last month and prosecutors are expected to present formal charges soon as part of the deepening kickback scandal engulfing Petroleo Brasileiro SA, as the oil major is formally known.
Brazilian federal police investigators are looking into reports that Pedro Barusco, a former executive at Petrobras' services division, and Paulo Roberto Costa, former head of the refining and supply unit, took bribes from Odebrecht.
The Swiss statement follows declarations from authorities in Latin American countries including Peru, Ecuador and Colombia that are collaborating with Brazil or investigating potential corruption in Odebrecht projects themselves.
Investigators in the United States and Panama also have been collaborating with Brazil as the global implications of the corruption investigation grow.
Brazilian prosecutors have said Odebrecht may have led what they call a cartel of engineering firms accused of overcharging Petrobras for contracts and distributing the excess money as bribes among themselves and to politicians, mostly members of parties in President Dilma Rousseff's governing coalition.
The Brazilian conglomerate, which accounts for nearly three quarters of infrastructure built by Brazilian companies abroad, said in a statement that it would solicit information from Swiss authorities to understand the scope of the investigations and the motive for including it as part of the Petrobras probe.
Brazilian prosecutors also have opened a separate inquiry into whether former President Luiz Inácio Lula da Silva improperly used his connections overseas to benefit Odebrecht after leaving office. Lula's institute has said all his activities with the company were legal. (Reporting by Katharina Bart; Writing by Tom Miles and Caroline Stauffer; Editing by David Goodman and Paul Simao)