LONDON — The authoritative military magazine Jane's Sentinel published a lengthy, detailed report this week that threatened to blow the lid off Israel's undercover agencies.

The 70-page story offers an intimate and comprehensive account of the structure of the Mossad, Israel's famed foreign intelligence agency, and the domestic intelligence agency, the Shin Bet.

The report contains a huge range of information, from the number and nature of weapons systems to the location and function of military training bases, storage sites for Israel's alleged nuclear arsenal, military doctrine, and the organizational structure of the intelligence services.

According to the report, the Mossad has about 1,200 employees and can "call on the help of many thousands of contacts around the world, especially among the Jewish diaspora."

The Mossad has several departments, the largest of which — the Collections Department — is responsible for intelligence-gathering abroad. The department has a number of "desks," which cover different parts of the world and control case officers.

The Political Action and Liaison Department deals with friendly foreign intelligence agencies, while a separate department deals with psychological warfare.

A clandestine operations command, answerable directly to the head of the Mossad, currently Danny Yatom, is known as Metsada, and operates small units of combatants who conduct missions abroad against those considered to be a threat to Israeli security.

These missions, according to the report, have included assassinations and sabotage.

One of the most important of the support units is the Research Department, which has 15 sections, or desks, each focusing on a different part of the world, with particular emphasis on the Arab world.

There is one desk each for the United States, Canada and Western Europe, Latin America, the former Soviet Union, China, Africa, the Maghreb (Morocco, Algeria, Tunisia), Libya, Iraq, Jordan, Syria, Saudi Arabia, the United Arab Emirates and Iran.

In addition, there is a "nuclear" desk, which specializes solely in tracking developments connected to nuclear issues.

Other intelligence units include the General Security Service (Shin Bet) and Military Intelligence, which the report says, coordinates the collection and analysis of electronic and communication intelligence, as well as intelligence from other sources.

It notes that Israel gathers intelligence from unmanned aerial craft and also makes use of the Sayeret Matkal, which is described as "Israel's top counterterrorism and intelligence-gathering unit."

One of the article's most surprising revelations is that Lekem, the Scientific Affairs Liaison Bureau, is still operating.

It was allegedly Lekem, a unit in the Prime Minister's Office, which controlled Jonathan Pollard, the U.S. Naval analyst who was convicted of spying for Israel and sentenced to life imprisonment in 1986.

His conviction caused a deep rift in U.S.-Israel relations. Israel claimed Lekem was a "rogue" intelligence organization, and promised the Reagan administration that the unit had been disbanded.

However, according to the report, "some sources claim the work of Lekem is still carried on by a unit working under the aegis of the Ministry of Foreign Affairs."