Britain supports action taken by Saudi Arabia and other Gulf states against rebels in Yemen who have forced the country's president to flee, Downing Street has said.

Saudi Arabia has bombed military installations in Yemen after receiving a request for help from President Abed Rabbo Mansour Hadi, who left the country by sea as the Shiite rebel group known as the Houthis pushed towards the port city of Aden.

The air strikes had the support of several other countries in the region, but were condemned by Iran, which described the operation as an "invasion" and a "dangerous step" that will worsen the crisis.

Saudi Arabia and its allies believe the Houthis are tools for Iran to seize control of Yemen, though the Houthis deny they are backed by Tehran.

A Downing Street spokeswoman said: "We support the Saudis and Gulf Co-operation Council in the action they are taking. They are doing so in response to a direct request from President Hadi for help to protect his country from Houthi aggression."

Saudi-owned Al-Arabiya News reported that the kingdom had deployed 100 fighter jets, 150,000 soldiers and other navy units in what it called Operation Decisive Storm.

The United Arab Emirates, Kuwait, Qatar and Bahrain joined Saudi Arabia in a statement saying they would answer a request from Mr Hadi "to protect Yemen and his dear people from the aggression of the Houthi militias which were and are still a tool in the hands of foreign powers". Support was also voiced by Egypt, Jordan, Pakistan, Morocco and Sudan.

Oman, the sixth member of the Gulf Co-operation Council, did not sign the statement.