The 29-year-old has impressed for the Premier League club this season, and fared particularly well during their recent 1-0 home defeat to Manchester United last Saturday.
However, it seems as though the Bundesliga 2 side are intent on seeking a buyer for the defender due to their relegation last season, regardless of whether Martin Jol's side decide to make the temporary stay a permanent one.
|7/1||Fulham are 7/1 to beat Norwich 1-0 with Coral
"[Riether's] made a good name for himself. Even if Fulham wouldn't want him, another club will come," Jakobs told Express.
However, Riether's agent Volker Struth does not share Jakobs' view that his client will definitely be making a departure from the RheinEnergieStadion in the summer.
"We were surprised hearing these statements from Cologne. Right now the situation is that Sascha will return to Cologne in the summer," Struth told reporters.
Koln's director Claus Horstmann revealed that Fulham have an option to buy the player - who can also operate in midfield - but insisted that no deal has been attempted yet.
"I've talked to Sascha in September. Fulham has got an option to sign him, it's not certain if they will make use of it," Horstmann said.
Riether has been an ever-present for Martin Jol's side this season, playing in all of the Cottagers' 25 league games.