LONDON (Reuters) - Goldman Sachs and the Wellcome Trust charity have made a joint bid to buy the commercial property portfolio of Britain's Network Rail, a spokeswoman for the Wellcome Trust said.

Sky News reported on Wednesday that the U.S. investment bank and the British medical charity have tabled a 1.2 billion pound bid for about 5,500 premises owned by National Rail, the British state-backed entity which is independently run.

Goldman Sachs and Wellcome Trust declined to confirm details of the bid.

"Wellcome Trust and Goldman Sachs have submitted a non-binding indicative offer for the commercial estate of Network Rail," a spokeswoman for Wellcome Trust said in an emailed statement.

A spokesman from Goldman Sachs confirmed the news but declined to comment further.

(Reporting by Sarah Young; additional reporting by Emma Rumney; editing by Costas Pitas and Susan Fenton)