The fourth bidder is Absolute Radio, a radio consultancy which is believed to be fronting a bid on behalf of its biggest shareholder, Dublin-based property company Landmark Enterprises.
The Malaysian company is called Astro All Asia Networks and is backed by Malaysian billionaire Ananda Krishnan.
Krishnan, who has an estimated fortune of £3bn, also owns Maxis, one of south-east Asia's leading telecoms groups, as well as racetrack betting and lottery operations.
His name cropped up in 2006 when it emerged he had a 2.26% stake in UK media buying and market research company Aegis, and was backing the campaign by major Aegis shareholder, Vincent Bollore, to secure seats on the company's board.
A private equity firm, Vitruvian Partners, was earlier knocked out of the running.
The deadline for the next round of bids for Virgin Radio is in mid-March.
The range of bids is believed to be higher than the last time SMG attempted to sell Virgin in late summer, when analysts valued the company at around £60m.
SMG itself values Virgin on its books at £85m. SMG shares rose 3.45% this morning to 15p.