CAIRO — Thousands took to the streets of Yemen’s capital, Sana, on Sunday to protest a Saudi-led coalition airstrike that killed more than 140 people and injured hundreds a day earlier.
The Saudi military coalition, which receives US support, initially denied carrying out the air raid, which targeted a funeral attended by hundreds. But on Sunday it called the bombing ‘‘regrettable and painful’’ and pledged an investigation.
It added that American experts would join in the inquiry, and also expressed ‘‘its deepest condolences and support’’ to the families of the victims.
The coalition, which is the only air power involved in the Yemen war, said its pilots ‘‘have clear instructions not to target populated areas and to avoid civilians.’’
The shift in the Saudi response came hours after a White House National Security Council spokesman said the Obama administration was ‘‘deeply disturbed’’ by the reports of the airstrike.
The United States has launched a review of its ‘‘already significantly reduced support’’ to the Saudi-led coalition and is ‘‘prepared to adjust our support so as to better align with US principles, values, and interests,’’ said the spokesman, Ned Price.
‘‘US security cooperation with Saudi Arabia is not a blank check,’’ Price noted.
In recent months, the Obama administration has faced mounting criticism for its backing of Saudi Arabia’s air campaign in Yemen. Lawmakers and human rights groups have urged a ban on US arms sales to Riyadh, declaring that Washington bears some responsibility for the civilian casualties in Yemen.
The coalition’s campaign has added to the civilian toll of the nearly two-year-long conflict between the Saudi-backed government and Shi’ite rebels. More than 10,000 people have been killed and millions are in the grip of a worsening humanitarian crisis.
In Sana on Sunday, many of those protesting outside the offices of the United Nations were supporters of the rebels, known as Houthis, who control the capital and much of northern Yemen, and loyalists of former president Ali Abdullah Saleh.
They chanted slogans against Saudi Arabia and its royal family, according to local news reports.
‘‘After this massacre, we are more determined to confront the assailants,’’ Mohammed Ali al-Houthi, a well-known Houthi leader, told the protesters, according to the Agence France-Presse news agency. ‘‘Open the fronts with the Saudi enemy immediately.’’
The Houthis and Saleh’s supporters are fighting against President Abed Rabbo Mansour Hadi, who was driven from the capital last year. Sunni Saudi Arabia has long been suspicious of the Shi’ite Houthis, who are widely suspected to be supported by Iran’s Shi’ite theocracy, Riyadh’s regional rival.
A UN official said more than 140 people were killed in Saturday’s bombing and more than 525 wounded, the Associated Press reported. It was one of the deadliest single attacks of the country’s civil war. The rebel-controlled Health Ministry gave a lower figure but said not all the bodies had been counted.
The funeral that was targeted was being held for Sheikh Ali al-Rawishan, the father of Galal al-Rawishan, the interior minister in the rebel-led government. Among those killed was Major General Abdul-Qader Hilal, head of the capital’s local council, officials said. Rawishan was seriously wounded.
The mourners included high-level officials, but also thousands of civilians, according to witnesses.
On Sunday, senior officials from the United Nations also condemned the attack, with Secretary General Ban Ki-moon demanding a ‘‘prompt and impartial’’ investigation. ‘‘Those responsible for the attack must be brought to justice,’’ he said.
In a separate statement, Stephen O’Brien, the UN undersecretary general for humanitarian affairs, said he was ‘‘horrified and extremely disturbed’’ by the attack and called for an investigation.
The attack ‘‘highlights once again the disproportionate risk for civilians when explosive weapons are used in urban areas,’’ O’Brien said.
Human rights groups have accused the coalition of gross human rights violations, including possible war crimes, claims that Saudi Arabia has denied.
The Houthis have been accused of recruiting child soldiers and carrying out forced disappearances of opponents.
While the Houthis and their allies have lost control of southern Yemen after 18 months of bombardment, they still hold Sana and much of the north, and have been launching regular attacks on Saudi Arabia’s southern borders.
About 3,799 civilians were killed in the Yemen war between March 2015 and Aug. 23, 2016, according to a recent UN report.
According to the report, coalition airstrikes were responsible for 60 percent of civilian deaths over a yearlong span starting in July last year.