Williams have signed a multi-year partnership with Brazilian oil company Petrobras, the Formula One team said on Tuesday.

The former champions had Venezuelan state oil company PDVSA as their biggest sponsor until Venezuelan Pastor Maldonado left at the end of last season.

They have now signed Brazilian Felipe Massa from Ferrari as one of their two drivers for 2014.

"Petrobras and Williams have had a successful partnership before and we are both looking forward to reuniting for 2014," said founder Frank Williams in a statement.
"Technologically they are very strong and that will be important for the team as the new regulations have made fuel efficiency increasingly important."