Clashes erupted on Thursday for a second successive night between Huthi rebels and loyalists of former president Ali Abdullah Saleh in the capital Sanaa, witnesses and security sources said.

Security sources close to Saleh said armed supporters of the Huthis had surrounded the residences of local officials in the rebel government who are linked to the former president.

Saleh loyalists were also seen taking up positions in the streets of the rebel-controlled city, witnesses and a security source there said.

Saleh and the Huthis forged an unlikely alliance in 2014, ending decades of animosity to join ranks in fighting against Yemen's internationally recognised government.

The infighting now threatens to unravel the fragile alliance, which has been battling the Saudi-backed government of President Abedrabbo Mansour Hadi in Yemen's devastating war.

Thursday's violence comes 24 hours after clashes at the Saleh mosque in Sanaa late Wednesday killed nine Huthi rebels and five Saleh supporters, according to multiple medical sources at hospitals in the capital.

One source at the Jumhuriya hospital on Thursday said the death toll had risen to as many as 18 rebels and six Saleh loyalists. The numbers could not be confirmed by other hospitals in the area.

The latest clashes erupted hours after tens of thousands of Yemenis packed Sanaa's Sabaeen Square to mark the Prophet Mohammed's birthday, heeding a call from rebel chief Abdul Malik al-Huthi.

But the rally was brief and people quickly returned home amid fears of new violence, as armed supporters of both sides deployed in the streets.

A source in Saleh's forces said Huthi fighters were positioned around the residences of two of the ex-president's nephews.

- Missile attack on Saudi Arabia -

Also on Thursday, the Huthis, who are backed by Iran, said they fired a ballistic missile at Saudi Arabia and hit a military target, in the second such attack this month, after threatening to retaliate over a crippling blockade

"We confirm the success of our ballistic missile trial, which hit its military target inside Saudi Arabia," the Huthi-run Al-Masira television channel said.

A spokesman for the Saudi-led military coalition did not immediately respond to a request for comment.

"Should the blockade continue, we know what (targets) would cause great pain and how to reach them," the rebel leader said earlier in a televised speech.

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

"The General People's Congress and its allies hold Ansarullah 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," said the GPC.

The rebels' interior ministry blamed Saleh's forces for Wednesday's clashes.

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 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 Yemen 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.

source: AFP