A Saudi-led coalition should stop targeting Yemen's Sanaa airport, the United Nations said on Monday, as it prepared a plan to set up an air-bridge to airlift humanitarian workers into the country from Djibouti.

"No flights can take off or land while the runways are being repaired," the U.N. Humanitarian Coordinator for Yemen, Johannes Van Der Klaauw, said in a statement.

"I strongly urge the coalition to stop targeting Sanaa international airport and to preserve this important lifeline - and all other airports and seaports - so that humanitarians can reach all those affected by the armed conflict in Yemen."

A Saudi-led coalition has been carrying out air strikes in Yemen to drive back Iranian-allied Houthi rebels.