Britain “will not hesitate” to launch further strikes against Houthi rebels if the Iran-backed group continue to attack shipping in the Red Sea, Rishi Sunak has said.

The Prime Minister issued the warning after US and British warplanes struck eight targets connected to the Iran-backed group in Yemen, including an underground storage site and locations linked to the militia’s missile and air surveillance capabilities.

“We are not seeking a confrontation,” Mr Sunak said in Parliament on Tuesday. “We urge the Houthis and those who enable them to stop these illegal and unacceptable attacks.

“But, if necessary, the United Kingdom will not hesitate to respond again in self-defence,” he said. “We cannot stand by and allow these attacks to go unchallenged. Inaction is also a choice. I believe it is the wrong one.”

The latest US-UK strikes against the Houthis were a show of force to demonstrate that “we back our words and our warnings with action,” said Lord Cameron, the foreign secretary.

He added the strikes were meant to “send the clearest possible message” to the Houthis that their attacks on Red Sea shipping “are illegal” and “unacceptable.”

Since the US and Britain first began targeting the Houthis on January 11, the rebel group has launched more than a dozen attacks on shipping in the Red Sea, Lord Cameron said.

“We will continue to degrade their ability to carry out these attacks,” he said.

The UK and US strikes on Monday were supported by Australia, Bahrain, Canada and the Netherlands, the six countries said in a statement.

US fighter jets from the carrier USS Eisenhower were involved in the night raid, while Britain sent four Royal Air Force Typhoons and a pair of Voyager tankers, according to the Ministry of Defence (MoD).

The British Typhoons used precision-guided Paveway IV bombs to strike several targets at two military sites near the Sana’a airfield.

“These locations were being used to enable the continued intolerable attacks against international shipping in the Red Sea,” the MoD said, adding that “a very rigorous analysis was applied in planning the strikes to minimise any risk of civilian casualties”.

The Prime Minister told MPs on Tuesday that the Government’s initial evidence was that “all intended targets were destroyed”.

Footage released by the MoD showed the Typhoons taking off from RAF Akrotiri in Cyprus at the start of the bombing mission.

Britain and the US have consistently warned the Houthis to stop attacking civilian vessels in the Red Sea. 

The Houthis, however, have not halted their operations, launching more than 30 missile and drone attacks on international and commercial vessels since mid-November and vowing to take revenge against “every aggression” by the US and UK.

Mohammed Ali al-Houthi, a top Houthi leader, said on Tuesday: “We say to the Americans and the British… Trust well that every operation and every aggression against our country will not be without a response, and expect a response every minute, if not every second, then every minute it must.” 

The Houthis say their attacks are in solidarity with Hamas, another Iranian-backed Islamist group that has been locked in a brutal war with Israel since October.

Vice-Adml Brad Cooper, head of the US Navy’s 5th Fleet, told the Associated Press in an interview that Iran is “very directly involved” in ship attacks that the Houthis are carrying out.

While Iran is not conducting the individual attacks, experts believe that the Houthis are acting with the assistance of Iranian intelligence.

Iran and Israel have long been engaged in a shadow war, with Iran offering training, weapons and financial support to various groups in the region that share the similar aim of challenging Israel.

In December, the US launched an international coalition to patrol the Red Sea, in addition to the military strikes against the Houthis.

“Our aim remains to de-escalate tensions and restore stability in the Red Sea,” said Tuesday’s joint statement from the US, UK, Australia, Bahrain, Canada and the Netherlands.

“Let us reiterate our warning to Houthi leadership: We will not hesitate to defend lives and the free flow of commerce in one of the world’s most critical waterways in the face of continued threats.”