Sunderland have approached QPR over defender Steven Caulker who is on loan at Southampton

Sunderland have approached QPR over the permanent signing of defender Steven Caulker, according to Sky sources.

The centre-half is currently on a season-long loan with Southampton but it is understood that if both clubs and the player agree, then he will be allowed to talk to Sam Allardyce's side.

Earlier, Saints boss Ronald Koeman said he wanted to keep the player until the end of the season.

Sunderland manager Sam Allardyce

Koeman said: "My plan is that he stays until the end of the season, and then we need to make a decision."

The 24-year-old started his career at Tottenham but, after a number of loan spells, joined Cardiff for £8m before moving to QPR.

He joined Southampton on loan in the summer but has found his opportunities at St Mary's limited with Virgil van Dijk and captain Jose Fonte preferred at the back.