Aug. 31 (UPI) — At least 11 United Nations employees in Yemen were abducted by Houthi-controlled authorities Sunday after they raided World Food Program facilities in the capital Sanaa.

U.N. Secretary-General Antonio Guterres announced and condemned the abduction in a statement that also demanded the “immediate and unconditional release” of those detained.

The U.N.’s WFP provides life-saving food assistance to children and mothers in a country considered one of the world’s worst humanitarian crises due to the nearly 12-year civil war between the Houthi militants and the internationally recognized Yemeni government.

The raid followed Israeli airstrikes on Houthi-controlled Sanaa on Friday, which killed its prime minister, Ahmed al-Rawai, along with several other ministers.

Sunday’s arrests increases the number of U.N. workers detained by the Houthis to 23, some whom have been in captivity since 2021 and 2023, Hans Grundberg, U.N. special envoy for Yemen, said in a separate statement.

“The work of U.N. personnel is designed and conducted under the principles of neutrality, impartiality, independence and humanity,” Grundberg said.

“These arrests violate the fundamental obligation to respect and protect their safety, dignity and ability to carry out their essential work in Yemen.”

Both Guterres and Grundberg confirmed that U.N. property had been confiscated by the Houthis during their Sunday raid, though exactly what taken was not detailed.

Both officials also demanded that the Iran-backed Houthis unconditionally release all U.N. personnel and staff from national and international NGOs, civil society organizations and diplomatic missions who have been taken over the years.

“The personnel of the U.N. and its partners must never be targeted, arrested or detained while carrying out their duties for the U.N.,” Guterres said.

“The safety and security of U.N. personnel and property as well as the inviolability of U.N. premises must be guaranteed at all times.”