By Chelsea correspondent Tony Hughes

Chelsea have registered their interest in Radamel Falcao as they pursue striker back-up to Diego Costa, Football Insider sources understand.

Blues manager Jose Mourinho has sanctioned a move for the Colombia international, who flopped during his season-long loan at Manchester United.

Mourinho is in the market for a third senior striker to provide competition for places next season to Costa and Loic Remy following the release of Didier Drogba.

Falcao has instructed his representatives to find him another club following United’s decision not to take up the option to extend his season-long loan into a permanent deal.

Manager Louis van Gaal informed the striker, 29, last week that his record of four goals in 29 United appearances was not enough to justify his retention.

The Colombia international, who is represented by super-agent Jorge Mendes, is not expected to return to Monaco and will now look for a club who can come close to matching his salary expectations.

He has been offered to Europe’s richest clubs, including Arsenal, but Arsene Wenger is not interested in taking on Falcao.

However, Mourinho could be prepared to offer Falcao a lifeline if a deal can be agreed in which the forward accepts a drop in his £275,000-a-week Monaco salary.

Chelsea are assessing various striker options, with QPR’s Charlie Austin among those on the club’s target list.

Falcao will now attempt to use the Copa America as a shop window following a difficult 18 months in his career in which a knee ligament injury has been followed by difficulties with his form and fitness.