Celtic have reportedly 'run checks' on two potential defensive targets.
Despite signing right-back Hatem Abd Elhamed recently, manager Neil Lennon is still eyeing two players who play in the same position after the departure of Mikael Lustig for Gent.
According to the Daily Mail, Celtic are interested Basel's Silvan Widmer and Antonio Barragan of Real Betis.
Widmer has won nine caps for Switzerland, while former Liverpool defender Barragan has been at Real Betis for two seasons after making 151 appearances for Valencia.
Despite their hunt for reinforcements, former Leicester right-back Danny Simpson recently had a trial with the Scottish champions cancelled.