Sana'a International Airport has not been a military target since 2016, and it's a civilian location, says UN Resident and Humanitarian Coordinator in Yemen.

A UN official expressed concern on Friday over Israel targeting key facilities in Yemen, including an airport, where a UN worker was injured.

"The bigger issue is parties to the conflict have an obligation to ensure that they are not striking civilians. The obligation is on them, not on us. We don't need to prove we're civilians. They need to prove that they are hitting a military target," Julien Harneis, UN resident and humanitarian coordinator in Yemen, told reporters.

His remarks came a day after Israel struck targets in Yemen, including the Sana'a International Airport, as World Health Organization (WHO) Director-General Tedros Adhanom Ghebreyesus was about to board a flight.

A UN worker was injured in the attack, and evacuated to Jordan for further treatment, Tedros said.

The WHO chief was in Yemen to negotiate the release of UN staffers who have been held hostage by the Houthi group for several months and assess the health and humanitarian situation in the war-torn country.

Harneis said Sana'a Airport has not been a military target since 2016, and it's a civilian location.

"It is used by the United Nations. It's used by the International Committee for the Red Cross. It is used for civilian flights ... So, all parties to the conflict have an obligation to respect the civilian nature of that facility and to observe international humanitarian law. The responsibility is on them," he added.

The Houthis have targeted Israel as well as Israeli-linked shipping and naval vessels in the Red Sea in solidarity with the Palestinian people in the Gaza Strip, where Israel has killed more than 45,000 people since an Oct. 7, 2023 cross-border attack by the Palestinian group Hamas.

The US and UK have also been bombing Houthi targets in Yemen.

Turning to the dire situation in Yemen, Harneis said as a result of the 10-year conflict, 18 million people in need of humanitarian assistance.

"Next year, as a result of worsening economic conditions, as much active fighting, because of the worsening economy, we expect that number to increase to 19 million," he stressed.