The Victorian Environment Protection Authority is the latest oBike detractor to take aim at the embattled bike-sharing company.

After months of finding the yellow bikes abandoned around the city, in the Yarra River and up trees, a string of complaints about dumpings around the Shrine of Remembrance caused the EPA to contact oBike and demand some action.

EPA chief executive Nial Finegan told radio station 3AW that the Singaporean company still had many questions to answer about its management system.

"How are they dealing with complaints? How are they dealing with the abandoned bikes?" he said.