European Transport Commissioner Antonio Tajani had said he was interested in consolidating airlines but had to review the deal properly, Mayrhuber told ORF Austrian radio.
"(Tajani) pointed out to me that it was in his interest too that airline consolidation could progress, but that he also had to make sure that there was a proper legal review," said Mayrhuber, who met Tajani last week in Brussels.
The European Commission is probing two aspects of the deal: whether it hampers airline competition and whether a EUR500 million euro (USD$685 million) subsidy by the Austrian government which is part of the deal constitutes illegal state aid.
Mayrhuber said that he was now more cautious than six months ago, when he would have said that there was absolutely no doubt the deal would be approved. But he still thought the reasons for approving it were overwhelming.
"It would be clearly logical that we'll get approval without conditions," he said. "On the other hand I take note that it takes a long time, that it is investigated very closely."