SINGAPORE, Nov 7 (Reuters) - Columbia Asia, a Southeast Asian healthcare firm backed by TPG, has emerged as the frontrunner to buy Malaysia-based private hospitals operator Ramsay Sime Darby Health Care for around $1.5 billion, said two sources with direct knowledge of the matter.

The acquisition will be the largest Southeast Asian healthcare acquisition since 2019 when Malaysian conglomerate Hong Leong Group and alternative asset firm TPG bought Columbia Asia's assets for about $1.2 billion.

Started in 1996, Columbia Asia currently has 22 medical facilities in Malaysia, Vietnam and Indonesia and focuses on building mid-size hospitals in residential areas, according to its website.

The firm is competing with a consortium comprising of Hong Kong-based private equity firm Affinity Equity Partners and Indonesia-based hospital operator Mitra Keluarga in the final round of the bidding process for the Asia-focused healthcare joint venture of Australia's Ramsay Health Care and Malaysia's Sime Darby, according to the sources. They declined to be named as the information remained confidential.

A deal could be concluded as early as within this week, the sources said, cautioning that last-minute changes are possible.

Ramsay, Australia's largest private hospitals operator, and conglomerate Sime Darby had hired Bank of America and Deutsche Bank to advise on the sale, Reuters reported in July.

Ramsay Sime Darby referred Reuters' request for comment to Ramsay and Sime Darby. Ramsay, Deutsche Bank, TPG declined to comment.

Sime Darby, Columbia Asia, Affinity Equity Partners, Mitra Keluarga and Bank of America did not immediately respond to requests seeking comment.

The sale of Ramsay Sime Darby comes at a time when healthcare assets are attracting more interest as investors bet on the sector's ability to weather tough economic conditions.

Ramsay Sime Darby was set up in 2013 through an equal joint venture to expand both firms' healthcare business in Southeast Asia. It has hospitals in Malaysia and Indonesia, including Subang Jaya Medical Centre in Selangor and RS Premier Surabaya in Jawa Timur.

An earlier effort to sell Ramsay Sime Darby to IHH Healthcare fell through last September, soon after a KKR & Co Inc-led consortium withdrew a near $15 billion offer for Ramsay.

IHH, one of Asia's largest private healthcare groups, had presented a 5.67 billion Malaysian ringgit ($1.21 billion) offer for Ramsay Sime Darby, but a binding agreement could not be reached. ($1 = 4.6680 ringgit) (Reporting by Yantoultra Ngui; Editing by Miral Fahmy)