Fighting follows heightened tensions between the Saleh and Houthi camps after their leaders traded accusations last week
Pro-Saleh colonel killed in fighting with Houthi allies in Sanaa
Yemen's rebel-held capital was on edge on Sunday after a senior aide to former president Ali Abdullah Saleh was killed following a confrontation with Houthi rebels, increasing tensions between key allies in the country's civil war.
Fighting broke out after a convoy carrying Colonel Khaled Al Radhi and one of Mr Saleh's sons, Salah, was stopped at a Houthi checkpoint near Al Misbahi roundabout in Sanaa late on Saturday, residents said.
They said the Houthis manning the checkpoint asked the guards accompanying the convoy to declare their affiliation, but they refused, leading to an exchange of insults.
The armed guards left their vehicles and started shooting at the Houthis, who returned fire. The fighting continued for several hours, residents said.
Mr Saleh's General People's Congress party announced the death of Al Radhi on Sunday but did not directly blame the Houthis, while the rebels said two of their fighters were killed.
Al Radhi was a close aide of Mr Saleh and deputy of head of his party's foreign affairs office.
Some local news websites reported that Salah was injured in the clashes, but there was no confirmation of this.
The clashes on Saturday came after a war of words broke out last week between the Houthis and Mr Saleh. The rebels accused Mr Saleh of being a traitor, while the former president dismissed the Houthis as a "militia" and accused them of corruption.
A resident of the upscale Hadda area where the fighting took place said the Houthi checkpoint was set up only recently near the house of another of Mr Saleh's sons, Ahmed Ali, and that the sons' convoys regularly passed through the area.
"We live near Al Misbahi roundabout and we started to feel that this area is dangerous because we are near the house of Ahmed Ali," he told The National. "The forces in this area used to be supporters of Saleh but the Houthis started to spread in this area during the last few days."
The Iran-backed Houthis and Mr Saleh's forces have so far fought side by side in the civil war that broke after the rebels overran Sanaa in September 2014, forcing president Abdrabu Mansur Hadi to eventually flee to the southern port city of Aden, where his government is currently based.
Mr Saleh was a bitter opponent of the Houthis during more than 20 years in power before being ousted in a popular uprising in 2012. Since his surprise alliance with the rebels, renegade military forces loyal to him have fought together with the Houthis against pro-government forces and the Saudi-led military coalition that intervened on behalf of Mr Hadi in March 2105.
The Houthis on Sunday downplayed the possibility that Saturday night's clashes would jeopardise the alliance.
"Col Khalid Al Radhi was killed during fighting, but both Ansarallah [the Houthis] and the General People's Congress party were wise enough to stop the fighting," a source in the Houthi interior ministry told The National. "Both sides did not escalate and they are trying to solve this problem."
The Houthi-controlled Saba news agency reported the clashes only as being between "security forces (the Houthis) and "armed men" (Saleh supporters), and said that a committee had been formed to investigate. It did not specify who would be on the committee.
However, the Hadda resident said Houthi and Saleh forces had started to spread out to several areas of Sanaa" "There is intensification from both sides, so people fear they will see a war between the two sides in Sanaa."
A rift between the Houthis and Mr Saleh could alter the course of Yemen's war, which has continued despite several attempts at a political resolution under UN auspices and has reached a stalemate, with rebels controlling most of the north while pro-government forces hold the south.
The coalition, of which the UAE is a member, continues to conduct air strikes against rebel positions and is supporting an offensive launched in January to retake Yemen's Red Sea coast from the rebels. However, the rebels still hold the key port of Hodeidah, through which the bulk of Yemen's imports pass.
The war has pushed the already impoverished country to the brink of famine, and killed more than 8,400 civilians.
The country also faces a deadly cholera outbreak that has claimed nearly 2,000 lives and affected more than half a million people since late April.
On Sunday the UN secretary general Antonio Guterres urged warring parties in Yemen to allow humanitarian aid into the country, namely by reopening the international airport in Sanaa and Hodeidah port.
The coalition imposed an air and sea blockade on all rebel-held territory in March 2015 to stop weapons being smuggled in to the rebels but has said it was willing to allow access to Sanaa airport and Hodeidah port if they were placed under UN control.
The coalition on Saturday expressed remorse for the deaths of civilians in an air strike that killed a number of civilians in Sanaa the previous day.
It said the attack in the Faj Attan area was targeting a Houthi command and control centre but resulted in civilian casualties because of a technical error.