ADEN — Saudi Arabia carried out airstrikes against Huthi rebels in Yemen, launching an operation by a regional coalition to save the government of embattled President Abedrabbo Mansour Hadi as the country teetered on the brink of civil war.

The airstrikes were announced by the Saudi ambassador to the United States as five Gulf states said they will answer Hadi's plea for intervention against the Shiite militia that has closed in on the city of Aden, were he took refuge after fleeing the capital Sanaa.

Qatar, Kuwait, Bahrain and the UAE along with Saudi Arabia said they "have decided to answer the call of President Hadi to protect Yemen and his people from the aggression of the (Shiite) Huthi militia."

Saudi envoy Adel al-Jubeir told reporters in Washington that the operation "is to defend and support the legitimate government of Yemen and prevent the radical Huthi movement from taking over the country."

Al-Jubeir said that for the moment the action was confined to air strikes on various targets around Yemen, but that other military assets were being mobilized and that the coalition "would do whatever it takes."

Saudi-owned Al-Arabiya news channel said Saudi airstrikes hit several targets in Yemen, including airbases and "destroying most Huthi air defenses."

Huge explosions were heard in Sanaa as strikes hit the airbase at Sanaa airport and other locations in the capital, an AFP correspondent reported.

In the south, residents reported hearing large blasts at Al-Anad main airbase, north of Aden, which was seized by anti-government forces Wednesday.

Rebels' television station Al-Massira also reported airstrikes on the capital.

Aden Under Threat

Acting foreign minister Riyad Yassin had warned in Egypt that the fall of second city Aden would mean the "start of civil war" as he drummed up Arab military support for Hadi.

His comments came as army units switched allegiance to the rebels and seized Aden's international airport.

Aides to Hadi said that the Western-backed president had been taken to a safe haven "within Aden," where he fled last month.

Washington said it had been in touch with Hadi and that he was no longer at his residence, but it was unable to say where he was.

Yemen has been gripped by growing turmoil since the Shiite Huthi rebels launched a power takeover in Sanaa in February.

The strife has raised fears Yemen could be torn apart by a proxy war between Shiite Iran, accused of backing the rebels, and Sunni-ruled Saudi Arabia, which supports Hadi.

The escalating turmoil in the country — which borders Saudi Arabia and lies close to key shipping routes — has also pushed up world oil prices on fears it could threaten Middle Eastern petroleum producers.

Hadi appealed to the UN Security Council on Tuesday to "shoulder its responsibilities ... to safeguard Yemen from sliding into more chaos and destruction."

One of Hadi's advisers said former president Ali Abdullah Saleh was the man pulling the strings as the rebels advanced.

"The Huthis are puppets in the hands of Saleh," the Riyadh-based Yassin Makkawi told AFP.

Dozens of people have been killed as the Huthis backed by troops allied to former strongman Saleh, have clashed with pro-Hadi forces as they push southwards.

Saleh, who resigned in 2012 following nationwide protests, has been accused of backing the Shiite rebels as he seeks to regain influence.

'Dagger' in Saudi Side

The acting foreign minister Yassin warned that domination by Iran would be a "dagger in the side of Saudi Arabia and the rest of countries of the Gulf."

His comments came after the Huthis said they had captured the defence minister in their push southwards deep into Lahj province, adjacent to Aden.

Gen. Mahmud al-Subaihi, who escaped house arrest in Sanaa this month, had been seen as a vital ally of Hadi in charge of organizing Aden's defense lines.

Missiles were fired from an unidentified warplane at Hadi's complex in Aden Wednesday, but only hit an abandoned building, a presidential security official said.

Rebels seized a Al-Anad key airbase 50 kilometers (30 miles) north of Aden on Wednesday, days after US military personnel were evacuated.

Yemen has allowed Washington to wage a long-standing drone war against al-Qaida in the country.

In his letter to the Security Council Tuesday, Hadi called for a binding UN resolution asking countries to provide immediate support "by all means and measures" to protect Yemen.

He voiced concerns that al-Qaida will "seize the current instability to spark further chaos."

The Council has so far only released a declaration of support for Hadi, during an emergency meeting the president requested Sunday.

Diplomats said no new meeting has been planned at this time.