Eavesdropping is “unacceptable” among close allies, Prime Minister Benjamin Netanyahu said Monday, ordering an official inquiry into reports that the United States had spied on Israeli leaders, including Netanyahu himself.

It was the first response from Netanyahu after weekend revelations that US and British intelligence services intercepted emails in his office and that of his predecessor Ehud Olmert, and also spied on former defense minister Ehud Barak.

“In the close ties between Israel and the United States, there are things that must not be done and that are not acceptable to us,” the prime minister said at a Likud faction meeting.

Netanyahu added he had requested a probe of the allegations.

“With regard to things published in the past few days, I have asked for an examination of the matter,” he said.

Netanyahu’s National Security Adviser Yossi Cohen is set to discuss the matter with his US counterpart Susan Rice and with US Secretary of State John Kerry in the near future, Israel’s Channel 2 news reported Monday night, citing parliamentary sources.

The prime minister’s comments closely mirrored those by other world leaders upon learning that Washington had eavesdropped on their communications. While the US and Israel consider each other close allies, ties between the countries have been strained of late over the issue of stopping Iran’s nuclear program and peace efforts with the Palestinians.

Documents leaked by NSA whistleblower Edward Snowden and published Friday said US and British intelligence agencies spied on the offices of Netanyahu and Olmert. The documents referred to email intercepts, but did not detail what information might have been exposed.

The New York Times, The Guardian and Der Spiegel reported Friday that Olmert, as well as then-defense minister Ehud Barak, were among more than 1,000 high-profile targets of surveillance in more than 60 countries; the documents were dated between 2008 and 2011. Israel’s Ynet added that the surveillance extended to email intercepts at Netanyahu’s office when he took over from Olmert as prime minister in March 2009.

At first, Netanyahu’s office did not formally respond to the report, but sources in Jerusalem were quoted saying that the Israeli leadership had not “fallen off their chairs” at the news that they were spied upon.

Netanyahu “is cautious and suspicious,” does not have a computer in his office, does not use email and does not have a private phone, Israel’s Channel 2 reported Friday night, “so they’d have to find other ways” to spy on him.

Yoel Goldman contributed to this report.