The Telegraph.co.uk reports RTL has formed a team that will be responsible for preparing a tender process for Five's sale.
A spokesman for Luxembourg-based RTL told MediaWeek.co.uk that the company "never comments on speculation".
He added: "Only so much - there will be further consolidation in the UK broadcasting market."
The spokesman's latter point is a clear indication that Five's owner is considering various options in regard to Five, including auctioning it off.
Speculation regarding Five's future and ownership has been rife, including rumours that it might merge with Channel 4. Last November there was even speculation that the terrestrial broadcaster might change its flagship channel from free-to-view to paid-for.
While the entire TV industry has been suffering from falls in advertising spend, Five's woes are exacerbated by what many would describe as a weak programming schedule. Five relies heavily on programme acquisitions for its content, such as US police drama CSI and Australian soap Neighbours.
Its last results speak volumes about its fortunes as a standalone entity. In March, Five reported a 2009 operating loss of €10m (£8.54m), a drop from its €2m operating profit in 2008.
Ad sales were hit hard by the recession. RTL reported that spot ad revenue at the Five family of channels, which includes Five US and Fiver, was down 23.6%, a fall that was still bad in the broader context of the overall TV ad market, which was down 12.5% year on year.