Thousands of mourners attended a funeral at the largest mosque in Yemen’s capital, Sanaa, on Monday for 12 senior Houthi figures, including their prime minister, who were killed by an Israeli strike.

Last Thursday’s attack, the first to kill top officials, struck a large number of people who had gathered to watch a televised speech recorded by top Houthi leader Abdul Malik al-Houthi, and it left most members of the group’s cabinet dead.

Mourners chanted the Houthi slogan “God is Great, Death to America, Death to Israel, Curse on the Jews, Victory to Islam”, as Mohammed Miftah, now de facto head of the Iran-aligned government in Sanaa, vowed revenge as well as an internal security crackdown against spies.

“We are facing the strongest intelligence empire in the world, the one that targeted the government, the whole Zionist entity (comprising) the US administration, the Zionist entity, the Zionist Arabs and the spies inside Yemen,” Miftah told the crowd of mourners at the Al Saleh mosque.

Miftah became the acting head of the Houthis’ government on Saturday following the death in the Israeli strike of Prime Minister Ahmad Ghaleb al-Rahwi. Al-Rahwi was largely a figurehead and not part of the inner circle of power.

Miftah had previously been his deputy.

A raid on the United Nations offices in Sanaa on Sunday led to the detention of at least 11 UN personnel, the body said. The Houthis have given no reason for the raid, but they have held a number of Yemeni employees of the UN and other aid agencies in the past on suspicion of spying.

Israel said on Friday its airstrike had targeted the Houthis’ chief of staff, defence minister and other senior officials and that it was verifying the outcome.

The fate of the Houthis’ powerful defence minister, Mohamed al-Atifi, who runs the Missiles Brigades Group, remains unclear as he has not made an appearance since the attack.