Prime Minister Benjamin Netanyahu recently extended to 90 years, from 70, the period of time that documents from organizations including the Mossad and the Shin Bet security service are to remain classified.

As a result, documents from 1949, the year the Shin Bet was founded will only be unsealed in 2039. Papers on the 2010 assassination in Dubai of Hamas Chief Logistics Officer Mahmoud al-Mabhouh, if such exist, will only be made public in 2100. The classification period was also extended for documents from the Israel Atomic Energy Commission, certain military units and the Israel Institute for Biological Research.

The Movement for Freedom of Information, the Association for Civil Rights in Israel and the Akevot Institute for Israeli-Palestinian Conflict Research all protested the decision, arguing that it is “arbitrary and disregards the great public interest in the revelation of archival materials.” The Prime Minister’s Office claimed there was a genuine security imperative to keep the material classified, despite its age.

>> A golden age for the Mossad: More targets, more ops, more money ■ Palestinians uncover history of the Nakba, even as Israel cuts them off from their sources ■ Why is Israel still covering up extrajudicial executions committed by a Jewish militia in '48? ■ What is Netanyahu hiding in the archive from 1948? | Analysis

The Supreme Council of Archives, an advisory body to the Israel State Archives that is subordinate to the Prime Minister’s Office, also opposed the 20-year extension. Last summer, the council advised an extension of just five years, but Netanyahu rejected the recommendation and last month signed an amendment to the archive regulations extending the classification period by two decades. The decision was made public this week.

“In a discussion of this type, we must bear in mind two contradictory thoughts,” former chief archivist Yaacov Lozowick said last summer at an Archives Council meeting on the matter. “The first is the great importance of the organizations (the Shin Bet and Mossad, etc.) and their activity, and the second is their oversight, for in a democracy, the right balance must be found.”

The legal advisor to the State Archives, attorney Naomi Aldouby, explained at the meeting that making these documents public “could genuinely harm national security.” For one thing, the material contains information about agents and informants, some of whom are still living, or have living descendants, who could be harmed by this information becoming known. And there is also information that was received from foreign sources and could harm Israel’s foreign relations. She also argued that some material pertains to methods of operation that were used in the early 1950s and earlier that “are still used today. If they were exposed, it could harm national security,” she said.

In response to a question from the Movement for the Freedom of Information, Aldouby wrote: “On the diplomatic and security fronts, Israel is still dealing with security challenges of the highest order, which require the utmost caution even 70 years after the state’s founding and the start of the time when the archival material in question was produced.”

She added: “The professionals believe that another 20-year period is a reasonable time, at the end of which it will be possible to reveal documents from the early days of the state without harming national security. ... Intelligence work is composed of mosaic of details, and it is difficult to assess the harm that could arise from the revelation of a single document. ... One document may certainly seem harmless in itself, but when combined with other seemingly harmless documents, it could provide a bigger picture that could end up harming national security. Rival intelligence agencies as well as terror organizations dedicated to collecting information could also extract intelligence insights from this material regarding the Israeli intelligence gathering and security organizations’ capabilities.”

At the same meeting last summer, David Amitai, chairman of the Association of Israeli Archivists, raised the possibility that the censorship of the documents was not due to security reasons but rather for the sake of protecting the country’s image. “When I look at [the 1948 documents], I have no idea how they could harm national security,” he said. “Yes, they’re not pleasant. Yes they could cause all kinds of scandals, but they won’t harm national security. Israel is strong enough to deal with unpleasant facts in war. Unpleasant things happen in war. ... In war there is looting and rape and lots of other things. Israel should be able to deal with these things.” Amitai argued that keeping such material classified here is “absurd” given that it is open to public view in the archives of other countries.

In practice, the decision has no real meaning, since these archives have always been completely closed to the public, says the Akevot Research Institute. Their query to the Prime Minister’s Office as to how much of the archival material from the Shin Bet and Mossad has been made public so far went unanswered.