Rangers want Dundee defender Luke Graham in the summer | OneFootball

Rangers want to sign Dundee defender Luke Graham, according to the Scottish Sun.

Manager Danny Rohl wants to strengthen at the back to mount a stronger challenge for the Scottish Premiership title next term.

Technical director Dan Purdy was at Dens Park on Saturday to watch Graham, and more scouting trips are expected ahead of the summer transfer window.

However, Rangers are not the only club monitoring the defender. Celtic and several English clubs are also keen.

Rangers could lose John Souttar at the end of the season as he has yet to sign a new contract.

Nasser Djiga is expected to return to Wolverhampton Wanderers after his loan spell ends, and Rangers are already preparing for life without the duo.

Graham will not come cheaply as Dundee rejected a £1 million bid from Portsmouth last month.

Rangers are two points behind league leaders Hearts after 27 games and are a point ahead of the Hoops in an intriguing title race.

Winning the title could help them sign Graham and other top players in the summer due to the lure of Champions League football.

The Scotland youth international has established himself as a key player this term after spending a couple of seasons out on loan.