The Saudi Press Agency reported that the latest attack against Houthi rebels in Yemen -- 130 airstrikes in a 24-hour period -- included the targeting of schools and hospitals.
The hospitals and schools that were hit functioned as weapons storage sites, coalition spokesman Brig. Gen. Ahmed Asiri said in a statement.
Asiri told CNN later that the press agency had mistranslated his words, and denied that the coalition has struck schools or hospitals.
"Someone asked me about how they (Houthis) have weapons if we destroyed so many of their depots," Asiri said. "I told him they are hiding them in hospitals, schools and hotels and they bring them out and use them."
He added: "Even though we know they are hiding things there, we don't hit them because we are worried about civilians."
Civilians had been warned ahead of time to leave the cities of Sadaa, Maran, Albiqaa and the border area between Saudi Arabia and Yemen, Asiri said.
In addition, the coalition spokesman accused the Houthi rebels of manning checkpoints that prevented civilians from leaving, in effect using them as human shields.
That rationalization for Friday and Saturday airstrikes was rejected by Johannes Van Der Klaauw, the U.N. humanitarian coordinator for Yemen.
"The indiscriminate bombing of populated areas, with or without prior warning, is in contravention of international humanitarian law," Van Der Klaauw said in a statement.
The U.N. official said he was especially concerned about the airstrikes on Saada, "where scores of civilians were reportedly killed and thousands were forced to flee their homes after the coalition declared the entire governorate a military target."
He also restated that "all parties must avoid using populated areas as launching grounds for attacks."
The Saudis say they want to restore the Yemeni government, a key U.S. ally in the fight against al Qaeda, which was kicked out of the capital by the rebels earlier this year.
But behind this explanation lies the influence of Iran in the region. The Saudis see the Iranian-backed Houthis as a threat, analysts say.
The Yemen conflict has claimed more than 1,400 lives since mid-March and nearly 6,000 people have been injured, Van Der Klaauw said.
NGOs criticize airstrikes
Before the latest round of airstrikes, two Houthi officials said the coalition dropped leaflets warning that the Saudis would consider the entire governorate of Saada as an enemy military zone starting Friday night.
Thousands of families evacuated Saada province -- which is in northern Yemen, close to the Saudi border -- throughout Friday.
Doctors Without Borders (MSF), one of the international aid organizations with a presence in Saada, confirmed the heavy bombing there.
"The bombing of civilian targets, with or without warning, is a serious violation of international humanitarian law," said Llanos Ortiz, MSF medical coordinator in Yemen. "It is even more serious to target a whole province."
It is impossible for an entire population to leave within a few hours, Ortiz said. Many Saada residents lack vehicles to flee or access to phone or other communication networks, he added.
One emergency coordinator for MSF, Teresa Sancristóval, said: "Even though the city is noticeably emptier many people were not aware of the order of evacuation -- it hasn't been heard by the entire population."
At least one hospital had to restructure its layout because of the airstrikes. The hospital is running out of safe places, so locations like the maternity ward were also being used as the pediatric and inpatient departments for women, Doctors Without Borders said.
The Saudi coalition spokesman said that the safety of Yemeni citizens matters equally to that of Saudi citizens, and emphasized the need for civilians to leave the targeted areas.
Asiri said the coalition feels "deep sorrow that the Houthi militia dared to prevent civilians from moving out of the two cities, through establishing checkpoints, controlling pumping stations and using civilians as human shields."
Diplomatic effort accompanies airstrikes
As the Saudi-led coalition carried out its airstrikes, it also floated an offer for a ceasefire starting on Tuesday.
Saudi Foreign Minister Adel al-Jubeir said that his country will implement a five-day ceasefire for Yemen beginning at 11 p.m. Tuesday.
His announcement came after the proposal was suggested in order to allow humanitarian organizations to bring much-needed aid into the wartorn Arab nation.
A Houthi-appointed Yemeni military spokesman, Kaleb Luqman, said that Yemen agrees with the proposed ceasefire.