Monaco’s Colombian striker Radamel Falcao requires surgery on the left knee injury he picked up in Wednesday’s French Cup tie which almost certainly rules him out of the World Cup.

News of the star striker’s operation was confirmed Thursday in a statement issued by his club and will have caused consternation back home in Colombia.

While the club did not specify how long they expected him to be out of action the news will raise huge concern in Colombia, who are drawn in Group C at the World Cup with Ivory Coast, Greece and Japan.

France’s former national team doctor Jean-Pierre Paclet hinted at a lengthy spell on the sidelines for Colombia’s key striker who has scored 20 goals in 51 international appearances.

“I don’t have his file in front of me but if there’s an operation it’s because his ligament is ruptured, in the best case scenario it’s six months (out) and his World Cup is over.”

Monaco revealed their record signing had suffered “an anterior cruciate ligament strain” in the 3-0 win at amateur side Chasseley.

It added: “Surgery is required. The doctors will do everything possible to enable Radamel Falcao to recover as quickly as possible.”

In Wednesday’s ill-fated game, Falcao crumbled to the ground following a challenge and needed lengthy treatment before being carried away on a stretcher just before the interval in his club’s victory over Chasseley.

Chasseley disclosed they have received e-mail threats in Spanish, and Soner Ertek, the player whose tackle inadvertently caused the injury, was forced to close his Facebook page after it was targeted with intimidating messages.

Chasseley’s club president Jocelyn Fontanel told AFP there had been no malice in Ertek’s tackle: “Accidents happen on the pitch. It wasn’t violent …

“It upset me the whole match, especially as I was beside the Monaco directors.

Falcao joined Monaco for 60 million euros ($A92m) last summer from Atletico Madrid.