Sirens sounded in areas of Jerusalem and the Dead Sea on Saturday as "a missile launched from Yemen was intercepted... prior to crossing into Israeli territory", the Israeli military said.

The day before, a fresh air strike hit Sanaa, which Huthi rebels blamed on "US-British aggression" though it remains unclear who was behind it.

There was no comment from Israel, the United States or Britain.

"I heard the blast. My house shook," one Sanaa resident told AFP late Friday.

The Iran-backed Huthis control large parts of Yemen after seizing Sanaa and ousting the government in 2014.

Since the eruption of war in Gaza in October last year, the Huthis -- claiming solidarity with Palestinians -- have fired a series of missiles and drones at Israel.

They have stepped up their attacks since November's ceasefire between Israel and another Iran-backed group, Hezbollah in Lebanon.

Israel has also struck Yemen, including targeting Sanaa's international airport on Thursday in an attack that came as the head of the World Health Organization was about to board a plane.

The Huthis have also attacked commercial shipping in the Red Sea, prompting reprisal strikes by the United States and sometimes Britain.

Earlier Friday, before the strike on Sanaa, tens of thousands of people gathered to protest and express solidarity with Palestinians.

"The equation has changed and has become: (targeting) airport for airport, port for port, and infrastructure for infrastructure," Huthi supporter Mohammed al-Gobisi said.

"We will not get tired or bored of supporting our brothers in Gaza."

- Airport damaged -

Israel's strike on the Sanaa international airport on Thursday shattered windows and left the top of the control tower a bombed-out shell.

A witness told AFP that the raids also targeted the adjacent Al-Dailami air base, which shares the airport's runway.

"The attack resulted in four dead until now and around 20 wounded from staff, airport and passengers," Huthi Deputy Transport Minister Yahya al-Sayani said.

It occurred as the head of the UN's World Health Organization, Tedros Adhanom Ghebreyesus, was preparing to fly out, and left one UN crew member injured.

Tedros was in Yemen to seek the release of UN staff detained for months by the Huthis, and to assess the humanitarian situation. He later posted on social media that he had safely reached Jordan with his team.

He said the injured member of the UN's Humanitarian Air Service "underwent successful surgery and is now in stable condition".

Israel's military did not immediately respond to a request for comment on whether they knew at the time that the WHO chief was there.

An Israeli statement said its targets included "military infrastructure" at the airport and power stations in Sanaa and Hodeida -- a major entry point for humanitarian aid -- as well as other facilities at several ports.

Huthis use these sites "to smuggle Iranian weapons into the region and for the entry of senior Iranian officials", the statement said.

But UN humanitarian coordinator Julien Harneis said the airport was "a civilian location" which the UN also uses, and the strikes took place as "a packed civilian airliner from Yemenia Air, carrying hundreds of Yemenis, was about to land".

Although the plane "was able to land safely... it could have been far, far worse", Harneis said.

In his latest warning to the Huthis, Israeli Prime Minister Benjamin Netanyahu said Israel's strikes would "continue until the job is done".

"We are determined to cut this branch of terrorism from the Iranian axis of evil," he said in a video statement.

Despite the damage, flights at Sanaa airport resumed at 10 am (0700 GMT) on Friday, deputy transport minister Sayani said.

- Yemenis depend on aid -

UN Secretary-General Antonio Guterres denounced the escalation in hostilities, and said bombing transportation infrastructure threatened humanitarian operations in Yemen, where 80 percent of the population depends on aid.

The United Nations has called Yemen "the largest humanitarian crisis in the world", with 24.1 million people in need of humanitarian aid and protection.

The airport is "absolutely vital" to continue transporting aid for Yemen, UN humanitarian coordinator Harneis said.

"If that airport is disabled, it will paralyze humanitarian operations."

After the attack on Sanaa airport, Huthis said they fired a missile at Ben Gurion Airport outside Tel Aviv and launched drones at the city and a ship in the Arabian Sea.

The Israeli military said the same day a missile launched from Yemen had been intercepted.

Israeli "aggression will only increase the determination and resolve of the great Yemeni people to continue supporting the Palestinian people", a Huthi statement said Friday.

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