LONDON - When British military leaders set up a special task force in 1969to study how best to use deception to achieve their battlefield aims, they focused on tactics used by the Israelis.

Formerly classified documents released Friday by the National Archives show that many officers felt the Americans, in contrast, did not have a knack for deceiving the enemy. Americans were judged to be so open and friendly that they lacked cunning.

The so-called Defense Deception Advisory Group studied the way Israel's military and political leaders used a complex series of intertwined deceptions to fool their Arab enemies about the Jewish state's intentions and its military capabilities.

The British found, for example, that the Israelis confused their adversaries by deploying fake soldiers - mannequins in battle dress were used - near a border crossing to make their enemies think an attack was coming, forcing them to deploy troops to defend the area.

"The British [were] impressed to see how those techniques could be used in a modern era," said Mark Dunton, contemporary history specialist at the National Archives.

The three-year study was prompted by fear that Britain's vaunted ability to deceive enemies in battle was fading because of the long period of relative peace that followed World War II. Its template was the Six-Day War in 1967.

After Egypt blocked the strategic Straits of Tiran and expelled UN forces from the Sinai Desert, Israel launched a preemptive strike on June 5, 1967 that destroyed Egypt's air force on the ground. In the ensuing six days of fighting, Israeli forces captured the West Bank, Golan Heights, Gaza Strip and Sinai from Jordan, Syria and Egypt.

The documents state that Israel implemented a sophisticated, preplanned deception strategy that included statements made by its political leaders and top diplomats during the tense prewar period. This included the well-known decision to send many Israeli soldiers on their regular weekend home leave to convince the enemy to lower its guard just before hostilities began.

An April 10, 1972, document credits the Israelis with using a variety of strategies to confuse and demoralize their enemies, including:

b Maintaining strict secrecy about modern bombs in their arsenal, leading Arab nations to believe Israel had only World War II-era bombs, and misleading the enemy about new systems that allowed Israel to service its bombers in just 7.5 minutes so they could resume attacks.

b Having Arabic-speaking Israeli agents take part in Egyptian military radio communications, giving them vital information about Egypt's military plans.

b Delaying information about the capture of key Arab towns, thus luring Arab patrols into devastating ambushes.

b Using Israelis who spoke Arabic with an Egyptian accent to man the control tower at a captured airfield so that Egyptian military pilots would land their planes and be captured.

b Using small deployments of tanks and torpedo boats to coax the enemy into defending borders where no real attack was planned.

The deployment of the dummy military units seemed to captivate the British: Typically deadpan officers used a rare exclamation point to describe the tactic.

Uri Bar-Joseph, a security and intelligence specialist at the University of Haifa, said this tactic led the Egyptian army to send units to the south when Israel planned to attack in the north.