Saudi Arabia has announced it is ending a month-long campaign of air strikes against the Houthi rebels who seized large areas of Yemen.

It said it would back a political solution to bring peace to its war-ravaged neighbour.

Iran, which has supported the fellow Shia Houthis, welcomed the ceasefire.

The announcement follows months of factional fighting between the militant group and forces loyal to the government, which was driven out of the capital Sanaa.

"Operation Decisive Storm has achieved its goals ... (including) removing the threat to Saudi Arabia and neighbouring countries, especially in terms of heavy weapons," said a statement carried by Saudi state news agency SPA.

It said a new phase called "Operation Restoring Hope" was beginning.

It would combine political, diplomatic and military action but would focus on "the political process that will lead to a stable and secure future for Yemen".

The White House tonight welcomed Saudi Arabia's decision to halt the air strikes, urging talks to end a crisis that threatened to draw regional powers into direct conflict. 

The World Health Organization said today that 944 people were reported killed and 3,487 wounded in Yemen in the four weeks up to Friday.

Rana Sidani, a WHO spokesperson, said the toll only covered data reported to the Ministry of Health by hospitals and the actual number of casualties was likely much higher.

Saudi spokesman Brigadier General Ahmed Asseri said the alliance may still target Houthis.

"The coalition will continue to prevent the Houthi militias from moving or undertaking any operations inside Yemen," he told reporters in Riyadh.

The Saudis called for a quick resumption of UN-facilitated talks to try to get a peaceful political arrangement for the country, which has a long history of internal fighting.

Saudi Arabia had earlier signalled a change in its mission by ordering its National Guard, to join the campaign, but did not say what role it would play.

The bloodshed in Yemen, racked by fighting between factions supported by different regional powers, had continued earlier in the day.

At least 40 people, most of them civilians, were killed in two air strikes.

The Houthis and military units loyal to the powerful former president Ali Abdullah Saleh have taken swathes of territory and forced the current president, Abd-Rabbu Mansour Hadi, into exile in Saudi Arabia.

The conflict created desperate shortages of food and other supplies in Yemen, where sea and airports are closed.

Houthi politburo member Mohammed al-Bukhaiti accused the United States of worsening the "siege" on the country by sending warships to the waters off Yemen.