The Israeli prime minister Benjamin Netanyahu has broken his silence over revelations that British and US spy agencies had targeted one of his predecessors, condemning the activities as “unacceptable”.

Papers leaked by Edward Snowden, and published by the Guardian on Friday, revealed that GCHQ in association with the National Security Agency had targeted an email address used by the Israeli prime minister when Ehud Olmert was in office.

Three further Israeli targets appeared on GCHQ documents, including another email address understood to have been used to send messages between the then Israeli defence minister, Ehud Barak, and his chief of staff, Yoni Koren.

“I have asked for an examination of the matter,” Netanyahu told members of his ruling Likud Party at a meeting of the parliamentary faction in the Knesset on Monday. “In the close relationship between Israel and the United States, there are things that are prohibited and that are unacceptable to us.”

Netanyahu had pointedly avoided addressing the growing storm at a meeting of the Israeli cabinet the previous day, prompting widespread media comment in Israel that he was attempting to stifle discussion on the embarrassing revelations about the behaviour of Israel’s closest strategic ally.

Israel has given undertakings not to spy on the United States since the arrest and life imprisonment of US naval intelligence analyst Jonathan Pollard in 1987 for spying on behalf of Israel.

Netanyahu and other Israeli leaders across the political spectrum, as well as senior retired US security officials, have unsuccessfully petitioned successive presidents to release Pollard, who has served a longer sentence than any other spy in the US. Although Netanyahu repeated his claim on Monday that the two matters should not be connected, he pointedly met with Pollard’s wife Esther in Jerusalem and posted a video of their handshake on his YouTube channel in response to a new groundswell of protest demanding Pollard’s immediate release in light of the latest revelations.

“I have met with Esther Pollard and updated her on our ceaseless efforts to liberate Jonathan. He should have been released long ago. I think that’s understood by everyone here, and also understood by large and growing sectors in the United States,” said Netanyahu.

Israel and the US are locked in sensitive diplomatic manoeuvring around the peace talks with the Palestinians. This new issue could not have arisen at a worse time.

Several Israeli ministers had already broken ranks and protested publicly about NSA surveillance. Israeli anger at the US was exacerbated by a report in Yedioth Ahronoth, the country’s largest-selling newspaper, that a US marine rented an apartment in June 2009 directly opposite the private home of Ehud Barak, a former prime minister and military chief of staff who was then Israel’s defence minister.

“Israeli intelligence detected sizeable amounts of electronic equipment delivered to the US-rented apartment,” Yedioth reported, together with diagrams of the sophisticated laser spying devices that might have been used to eavesdrop on Barak’s private conversations via the vibrations of the windows of his home.

Strategic affairs minister Yuval Steinitz and other officials said the NSA and GCHQ would have learned little of value from the email addresses and phone lines they apparently intercepted, which were publicly listed contact points and not used for the transmission of sensitive information.

Oved Yehezkel, a former military intelligence officer who was cabinet secretary to then prime minister Olmert, said it was assumed that communications between Israeli leaders were being monitored by their closest friends in Washington. “Of course we knew. Anyone who thinks that friends and allies don't spy on each other should re-read John le Carré,” Yehezkel said.