The supporters of Shiite Houthi rebels gathered outside UN offices in Sanaa and chanted slogans against Saudi Arabia and its royal family.

The rally took place a day after the Saudi-led coalition of Arab countries targeted a funeral procession in the Yemeni capital, killing at least 140 people and wounding more than 525.

Saudi Arabia launched an air campaign against Houthis in March last year. Riyadh accuses Tehran of backing the rebels, who have made significant territorial gains in the impoverished Middle Eastern country, capturing the capital Sanaa and ousting internationally recognized President Mansour Hadi.

Over 10,000 people have been killed and three million displaced since the start of the conflict. More than 21 million people - over 80 percent of Yemen's population - are in urgent need of aid, and some 9.4 million Yemenis have problems accessing water, the UN said.

"After this massacre, we are more determined to confront the assailants," rebel chief Mohammad Ali al-Houthi told demonstrators. "Open the fronts with the Saudi enemy immediately," he added, to which the crowd chanted anti-Saudi and anti-US slogans.

"Allahu Akbar (God is great). America is the Great Satan," they shouted at the rally that was dubbed as the "Volcano of Rage."

Review of coalition support

The Arab coalition initially denied bombing the funeral, but later said it was ready to investigate the "regrettable and painful" attack.

The attack has also embarrassed the US government, which since March 2015 has provided logistical support including in-air refueling and intelligence for the Saudi-led air campaign.

The US said Saturday it was reviewing its support for the Saudi-led coalition in Yemen.

"US security cooperation with Saudi Arabia is not a blank check," White House National Security Council spokesman Ned Price said in a statement.

The United Nations also condemned the Sanaa bombing, with Secretary-General Ban Ki-moon demanding a "prompt and impartial" probe.

"Those responsible for the attack must be brought to justice," he said.

UN under-secretary-general for humanitarian affairs and emergency relief, Stephen O'Brien, also demanded an investigation into the attacks.

"I also call on all parties to protect civilians and stop using explosive weapons or conducting aerial bombardments in civilian-populated places in Yemen. Surely enough is enough," O'Brien said. "This horrendous and heinous attack displayed an utter disregard for human life."

shs/rc  (AFP, Reuters)