The transaction will leave operator Shell with a 73% interest, up from 50%, in the heavy-oil development in the offshore BC-10 block, Shell said in a statement Monday.

Partner ONGC also increased its interest to 27%, up from 15%, in a $529 million purchase.

Petrobras said the deal - valued together at $1.63 billion - was approved by Brazil's National Petroleum Agency (ANP) on 18 December and closed Monday.