Israel is "a true threat" to the Middle East, according to the UK’s Government Communications Headquarters intelligence-gathering apparatus.
The 2009 top-secret document was part of a leak by American whistleblower, >as reported by Le Monde this week.
“The Israelis constitute a true threat to regional security, notably because of the country’s position on the Iran issue," the document said.
The report says that the UK's intelligence gathering on Israel is classified as "high level". It says that intelligence officers have monitored Israel's second-highest foreign ministry official, who was left unnamed.
Monitoring operations of the Palestinian Authority are also mentioned.
While it's not surprising that the British would be spy on an ally, the statement classifying Israel as a "threat" appears to counter the country's continual support for the Israeli government.
The United Kingdom was instrumental in leading the way to establishing the Israeli state. Prior to the formation of Israel, Palestine was under British governance.
In contrast, previous revelations from documents leaked by Snowden have shown that the United States National Security Agency was completely unconcerned by the Palestinian Authority's security forces.
It said these forces are "no threat to the United States or its allies…and these forces are frequently the best informed on violence in the region," according to Haaretz.
Although the US and the UK continually support Israel publicly, giving billions of dollars in military aid on a regularly basis, they often express frustration with the government's unwillingness to curb illegal settlements and human rights abuses.
US President-elect Donald Trump has tapped retired Marine Gen. James N. Mattis to be his Secretary of Defense in the new administration. Mattis has expressed critical views on Israel in the past.
He said that the US "pays a price" in the region for its support of Israel. He also said that settlements are a threat to the possibility of a two state solution and will lead to apartheid.