Royal Dutch Shell Plc is in talks to sell its assets in a Gulf of Mexico oilfield to Focus Oil to pay for its takeover of BG Group Plc, Bloomberg reported on Thursday, citing people familiar with matter.

The deal could value Shell's stake in the Caesar Tonga field at about $1.3 billion, the report said.

Shell has a 22.5 percent working interest in Caesar Tonga, with the rest owned by companies including Anadarko Petroleum Corp, Equinor ASA and Chevron Corp, Bloomberg said, citing company filings.

Shell and Focus Oil did not immediately respond to a request for comment.

(Reporting by Sathvik N in Bengaluru, Editing by Rosalba O'Brien)