SANAA - Tens of thousands of Yemeni rebel supporters gathered in Sanaa on Thursday a day after deadly clashes between the Huthis and their allies sparked fears of further violence in the rebel-held capital.

The clashes, which erupted late Wednesday near the capital's Saleh mosque, killed nine Huthi rebels and five supporters of former president Ali Abdullah Saleh, according to medical sources. The infighting threatens to unravel the fragile rebel alliance that controls the capital and has been battling the Saudi-backed government of President Abedrabbo Mansour Hadi in Yemen's war. The rally came after late-night mediation attempts between Saleh and the rebels failed to reconcile both sides, sources said.

Saleh and the Iran-backed Huthis, also known as Ansar Allah, have accused each other of inciting Wednesday's unrest.

"The General People's Congress and its allies hold Ansar Allah fully responsible for every drop of blood shed among the Yemenis... and warn against all acts that, rather than serve national unity, threaten our internal unity and cohesion," the party said in a statement.

The rebels' interior ministry blamed forces loyal to Saleh for the clashes in a statement released late Wednesday.

It said its security forces had been banned from entering the Saleh mosque by armed guards "not affiliated with the ministry", referring to Saleh's forces.

"We were surprised when these armed forces inside the mosque opened fire on police without warning, which forced police to fire back," it said.

The rift between Saleh and the Huthis goes back months, with the former president slamming the Huthis as "militias" and the rebels threatening Saleh loyalists after armed violence left two dead in Sanaa in August.

The Huthis have also accused the former president of accepting funds from the Saudi-backed Hadi government.

Yemen's conflict has claimed more than 8,600 lives since 2015, when Saudi Arabia and its military allies joined Hadi's government in the fight against the rebels.

The United Nations has warned that the country faces mass famine unless the Saudi-led coalition allows more food aid to enter the impoverished country.

Saleh ruled Yemen from its unification in 1990 until he resigned under pressure in 2012, ceding power to his then vice-president Hadi. He fought six wars against the Huthis when he was president, but joined forces with them to take over the capital in 2014.