Clashes in Yemen's capital between Houthi rebels
and loyalists of former president Ali Abdullah Saleh left 14 people dead on Wednesday, medics and officials said.
Fighting erupted around Sanaa's central mosque, the largest in Yemen, after Houthis tried to seize it ahead of Thursday's celebrations of the Prophet Mohammed's birthday.
"The Houthis attempted to take control of the mosque in anticipation of a rally on Thursday" in the adjacent square, said an official from Saleh's General People's Congress
, asking not to be named.
The mosque's guards, who were Saleh supporters, resisted, triggering a gunfight between the two camps, the GPC official said.
The shootout then spread to nearby districts controlled by Saleh loyalists.
The official said four Saleh supporters were killed on the spot and a fifth died of his wounds later in hospital.
Nine Houthi fighters also died in the fighting, according to officials at two hospitals in the capital.
Houthi rebel chief Abdulmalik al-Houthi had on Wednesday urged supporters across the country to head to Sanaa for the rally.
For decades sworn enemies, nationalist forces loyal to Saleh and the Iran-backed Houthis joined ranks in 2014 to drive the government of President Abedrabbo Mansour Hadi out of Sanaa.
That prompted a Saudi-led coalition to intervene the following year to prop up Hadi's government.
The war has since killed some 8,600 people, while a further 2,000 have died of cholera.
Despite a crippling coalition blockade, the Houthis and Saleh's forces continue to jointly control Sanaa, but tensions between them have escalated since a public dispute in August.
The Houthis accused Saleh of treason after the former president publicly dismissed the Iran-backed rebels as "militias".
Saleh's GPC party last month accused the Houthis of waging an "orchestrated campaign" against the former strongman and lacking "the will to maintain partnership".
The Houthis responded that the GPC had broken its pact by accepting funds from Hadi's government.