Rig contractor Ensco Plc said Petrobras has declared void a contract for a drillship leased to the Brazilian oil producer.
Petroleo Brasileiro SA, or Petrobras, chartered the DS-5 in 2008, when it was owned by Pride International, a company bought by Ensco in 2011.
Petrobras said in a notice on Monday that Pride had knowledge that the rig's shipbuilder made "improper payments" to a marketing consultant who then shared the money with former employees of Petrobras.
Ensco has denied allegations of corruption in Brazil.
