HONG KONG, Sept 4 (Reuters) - Hong Kong leader Carrie Lam is expected to announce later on Wednesday the formal withdrawal of a proposed extradition bill that sparked three months of protests in the Chinese-ruled city, the South China Morning Post reported, citing unnamed sources.

Other local media outlets also reported on a possible withdrawal of the bill. The chief executive's office did not immediately respond to request for comment.

The withdrawal of the bill, which would have allowed Hong Kong citizens to be sent to mainland China to face trial, is one of the main demands of pro-democracy protesters who have plunged the former British colony into its deepest crisis in decades. (Reporting by Farah Master; Writing by Joe Brock; Editing by Michael Perry)