The case has shocked Greeks and sparked political uproar.
The head of the intelligence service EYP, Panagiotis Kontoleon, resigned on Friday following allegations made by Socialist leader Nikos Androulakis and a journalist that they had been wiretapped.
Greece’s intelligence chief has resigned, the government said on Friday (5 August) amid a scandal over alleged spying of an opposition politician.
In a preview of Sunday’s To Vima newspaper, Mitsotakis was quoted as saying: “I wasn’t aware, I would have never allowed it. I owe Mr. Androulakis an apology for the mistake made.”
“It was a serious and unforgivable mistake,” he added.
The conservative premier is expected to make a public address over the case on Monday, the semi-state Athens News Agency reported on Saturday.