American intelligence officials have explained to their European counterparts why they failed to anticipate Hamas’s assault on Israeli villages, which was reportedly planned on telephone lines in hidden tunnels.

The Oct 7 attacks were prepared entirely inside Hamas’s close-knit military wing, meaning they were not detected by Israel’s informants inside the group’s political ranks, Europe’s spy agencies were told.

Those behind the plot also avoided digital channels that could be cracked by US and Israeli spies, relying instead on face-to-face meetings and phone lines installed inside the system of tunnels beneath Gaza, sometimes known as the “Gaza Metro”.

Israel’s failure to uncover Hamas’s plans and thwart the attacks, despite having some of the most renowned intelligence capabilities in the world, has alarmed its regional and European allies.

Officials said intelligence gathering had relied too heavily on high-tech eavesdropping and suffered a lack of informants, leaving both Israel and its US allies unaware of the coming assaults, Le Monde reported.

The US briefing also concluded that Hamas had received no outside support for the attacks from Iran or its Lebanon-based ally, Hezbollah.