It was the first time Israeli authorities have expressed anger since details of US spying on Israel began to trickle out in documents leaked by the former NSA contractor Edward Snowden.

The reports also spurred renewed calls for the release of Jonathan Pollard, a former American intelligence analyst who has been imprisoned in the US for nearly three decades for spying for the Israeli regime.

"This thing is not legitimate," the Israeli intelligence minister, Yuval Steinitz, told Israel Radio. He called for both sides to enter an agreement regarding espionage.

"It's quite embarrassing between countries who are allies," the tourism minister, Uzi Landau, said. "It's this moment more than any other moment that Jonathan Pollard [should] be released."

Documents leaked by Snowden – and published last week in the British daily Guardian, Germany’s Der Spiegel and the New York Times – revealed that British intelligence agency GCHQ worked with the NSA from 2008-11 to target email addresses belonging to the authorities of then Israeli prime minister, Ehud Olmert, and the defense minister, Ehud Barak.

Leading Israeli authorities work on the assumption that they are being monitored. Officials use special secure lines for certain types of communications, and for the most sensitive matters, issues are discussed only face to face in secure rooms.

Even so, Israeli officials reacted with uncharacteristic anger toward the US, Israel's closest and most important ally.

Espionage is a sensitive subject between Israel and the US because of the Pollard affair. Pollard, a former civilian intelligence analyst, was sentenced to life in prison in 1987 for passing classified material to Israel.

Israeli leaders frequently call for his release and say his nearly three decades in prison are punishment enough.

The US refuses to do so.

SHI/SHI