The four Spanish clubs involved the UEFA Cup have asked for Thursday’s ties to be postponed following the terrorist attacks in Madrid.
Barcelona are in Scotland to face Celtic while Real Mallorca are scheduled to play at Newcastle, Valencia at Genclerbirligi and Villarreal are at home to Roma.
At least 130 people are thought to have died following a series of explosions in the Spanish capital earlier today.
Celtic have already confirmed that they would support a postponement of their tie.
Officials from the Scottish club have already had discussions with Barcelona president Joan Laporta.
“Clearly all our thoughts are with the families of those affected by these tragic events in Spain,” said a Celtic spokesman.
“Celtic are fully supportive of Barcelona’s request for the postponement in light of those events and we are awaiting further communication from Uefa.
“Everyone is shocked by the events but as things stand Uefa are proceeding with the plans to play the game.”