At least 57 civilians have been killed and 130 wounded in the past 24 hours in airstrikes by a Saudi-led alliance in rebel-held areas in Yemen, a health official said Saturday morning.



The warplanes have carried out a series of strikes in the rebel-held capital, Sana'a, since Friday, killing 19 civilians and injuring 109, the official said on the condition of anonymity.



He added that 38 more civilians were killed and 27 wounded in bombing by the coalition jets in the northern province of Saada, which is the stronghold of the Iran-backed Houthi rebels.



There was no comment from the alliance.



Meanwhile, Oman said the residence of its ambassador in Sana'a was hit in an allied airstrike Friday. No casualties were reported.



"This bombing is a glaring violation of international agreements and norms," the Omani Foreign Ministry said in a statement.



Oman closed its embassy in Sana'a after the rebels seized the city in September.



In recent months, the Gulf sultanate has hosted several indirect talks aimed at ending the conflict between the rebels and loyalists of the internationally recognized President Abd Rabu Mansour Hadi.



In March, Saudi Arabia and its fellow Sunni partners began an air campaign in Yemen after the mostly Shiite rebels advanced on the southern city of Aden, forcing Hadi to flee the country.



Oman is not a partner to this campaign.



Hadi, a Sunni, is currently in Saudi Arabia.



More than 4,500 people have been killed in Yemen's conflict since March, UN agencies said.