Government troops and militias allied with the opposition exchanged fire overnight and on Thursday morning in Somalia's capital Mogadishu, damaging property and forcing some civilians to flee, residents told Reuters.

The violence flared up ahead of planned protests on Thursday over President Hassan Sheikh Mohamud's decision to remain in office after his term expired last month. Parliament in March backed constitutional changes that potentially allowed Mohamud to extend his term by a year and push back an election.

Former president Sharif Sheikh Ahmed, who was in power from 2009 to 2012, said government forces had targeted his home and accused Mohamud's government of "illegally altering the constitution."

"The government forces encircled and attacked my house. I am never scared of their aggressive attack, I will fight back," he said in a video on his Facebook account posted overnight.

In a post on X, former prime minister Hassan Ali Khaire accused government troops of using heavy weapons including anti-tank weapons and drones in a densely populated area. Reuters was not able to independently verify the claims.

Khaire added that the government had directed "a sustained and indiscriminate military assault" aimed at killing him and Ahmed.

Somalia's information and defence ministers did not pick up calls or respond to Reuters messages seeking comment.

WITNESSES REPORT CIVILIANS FLEEING, VEHICLES DESTROYED

Fighting began around 5 pm on Wednesday and continued into Thursday morning, with thousands of government troops deployed in Mogadishu's Howlwadag and Abdiasis districts, where they traded fire with militias supporting opposition leaders, residents told Reuters. 

"A mortar shell landed on my neighbour's house, injuring a mother. A big house near us is also ablaze, mortars and other weapons landed on it," one resident, Ahmed Ismail, told Reuters early on Thursday.

"In front of our house I see a man injured and carried by hand. Civilians keep on fleeing the war, I see them walking with kids in hand and cursing the two warring groups," he said.

At least two armoured vehicles were burnt by opposition-allied militias, Mohamud Farah, another witness, said.

Somalia has ​endured conflict and clan battles with no strong ⁠central government since the fall of autocratic ruler Mohamed Siad ​Barre in 1991. The country has also been grappling with a nearly two-decade-long insurgency led by the al Qaeda-linked al Shabaab group.

The US embassy in Mogadishu described the violence as "reckless".

"Somali leaders on all sides have a responsibility to preserve stability and resolve differences through peaceful means," it said in a post on X.

The UK also urged restraint and dialogue, saying the violence was unacceptable.