SINGAPORE, June 11 (Reuters) - Global infrastructure investors Actis and I Squared Capital are among companies considering bids for Beijing Capital Group's wholly-owned Singapore waste management company ECO, according to two sources with direct knowledge of the matter.

Others interested companies include Singapore's Keppel, the sources said, adding that the parties are working with financial advisers to weigh making binding bids for ECO Special Waste Management.

China's Beijing Capital had hired Citigroup last year to sell the company in a deal that could fetch $300 million to $400 million, Reuters reported in December.

Deadline for the bids are due as early as end of this month, the sources said, adding that deliberations are still ongoing with no final decisions made and the firms could decide against pursuing a deal.

The sources declined to be named as the matter was private.

Actis, I Squared and Keppel declined to comment. ECO, Beijing Capital did not immediately respond to Reuters' requests for comment.

Beijing Capital bought the business from private equity firm Navis Capital for S$246 million ($181.89 million) in 2015.

Investors' interest in Southeast Asia's waste management sector has grown amid the region's rapid growth in population and shift towards greener and cleaner energy and environment.

In 2022, a Keppel consortium bought a 80% stake in Singaporean environmental services firm 800 Super Holdings for S$304 million.

Beijing Capital operates in the wastewater treatment, water construction, and real estate development businesses in China.

It also has businesses in financial services and culture and sports sectors, its website shows.

ECO, founded in 1997, provides waste management services in Singapore and is located in Tuas View Circuit with facilities and a fleet of more than 40 waste collection vehicles, according to its website. ($1 = 1.3525 Singapore dollars)

(Reporting by Yantoultra Ngui; Additional Reporting by Ziyi Tang in Beijing. Editing by Scott Murdoch and Rashmi Aich)