Brazil’s federal police said the three former lawmakers and four other suspects were taken into custody on Friday.
Prosecutors have said the scheme involved alleged payments of at least $800 million in bribes and other funds by big construction and engineering firms in return for inflated contracts with Petrobras. Part of that that money allegedly went to the Workers Party and other top parties for political campaigns.
The three politicians are accused of involvement with black-market money dealers who have said they helped move the money around.