Yemen crisis: Saudi Arabia launches air strikes on Houthi rebels as four Egyptian naval ships cross Suez Canal en route to Red Sea

Kingdom's announcement was made by the ambassador to the US

Residents survey the devastation of Saudi air strikes this morning (AFP)

Four Egyptian naval vessels have entered the Suez Canal, heading towards the Yemeni coastal city of Aden in the latest escalation of hostilities in the region.

The actions follow Saudi Arabia's air strikes against advancing Houthi rebels in neighbouring Yemen, the country’s ambassador to the United States announced yesterday.

Adel al-Jubeir, speaking at a press conference in Washington, said Saudi Arabia “will do anything necessary” to “defend the legitimate government" of President Abd Rabbuh Mansour Hadi.

The president, a staunch US-ally, was forced out by rebels in January this year after Houthis seized the presidential palace.

Saudi Arabia will contribute 100 fighter jets, 150,000 soldiers and other naval units, according to the Saudi-owned TV network Al-Arabiya, as part of a coalition of approximately nine Arab nations.

Mr al-Jubeir claimed although the US and Saudi Arabia had consulted closely, the country was not involved in operations.

Secretary of State John Kerry held private meetings with Saudi Arabian officials, in which he reassured them of the US government's "support for those coalition efforts - including intelligence sharing, targeting assistance, and advisory and logistical support for strikes against Houthi targets," an anonymous state official told Reuters.

Ambassador Adel al-Jubeir, speaking at a press conference in Washington (Reuters)

Meanwhile Bahrain, Jordan, Kuwait, Morocco, Qatar, Sudan and the United Arab Emirates have pledged to contribute fighter jets, with Pakistan and Egypt offering naval support.

The four Egyptian ships en route to the region are expected to make the Red Sea by Thursday evening.

A senior Houthi rebel, speaking to a Reuters last night, warned that the Saudi aggression, alongside the involvement of other Gulf Nations, could set off a “wide war” in the region.

The Shia rebels, who the coalition and some western observers fear are backed by Iran, have made rapid advances in the past months.

An Iranian official denounced Saudi Arabia's decision, claiming it would serve only to escalate tensions in the region. However, the same Iranian official also ruled out military intervention, Reuters reported.

Supporters of the beleaguered Yemeni president claimed today government forces had retaken the strategically important Aden airport, just 35 miles from the country’s second largest city, after heavy clashes with Houthi rebels.

The Houthis, who deny that they are backed by Iran, control much of the north of the country – including the capital of Sanaa – and several southern provinces.

Saudi Defence Minister Mohammed bin Salman bin Abdul Aziz (2nd R) meeting with Saudi air forces officers (Reuters)

Their advances have been a further complication to US counterterrorism strategy against the powerful Yemeni branch of al-Qaeda.

The US recently withdrew 100 US military advisers withdrew from the al-Annad air base where they had been leading a drone campaign against the AQAP, al-Qaeda in the Arabian Peninsula.

In a separate development yesterday, secret files held by Yemeni security forces containing the details of American operations were reportedly looted by the rebels and handed to Iranian advisors, the Los Angeles Times claimed.

Yemen, among the most impoverished nations in the Arab world, now risks becoming the site of a battle-by-proxy as big players in the region weigh in.

Last night the whereabouts of President Hadi remained unknown as mixed reports indicated the encroachment of rebel forces, members of the Zaidi branch of Shia Islam, towards Aden.

As Yemeni officials denied reports of the president fleeing, Houthi-controlled state TV announced a ransom for the “fugitive” president.

Additional reporting by Associated Press