Thomson Reuters
The news comes months after Marriott International Inc agreed to buy Starwood for $12.2 billion to create the world's largest hotel chain.
Starwood did not disclose the names of the companies that made the approach.
Starwood shares rose by as much as 7% in pre-market trading after the announcement. The shares had fallen about 13% over the past year.
(Reuters editing by Saumyadeb Chakrabarty)