An explosive shell hit a funeral gathering attended by southern separatists in Yemen, killing 15 people, including children, on Friday, witnesses and medical sources said.
Witnesses said the shell had been fired by a tank and blamed the army. One local army officer, who asked not to be named, told Reuters a military outpost had fired the shell by mistake, and the man in charge was being investigated - though there was no immediate comment from the defence ministry in Sanaa.
Around 40 people were also wounded in the strike on a tent where mourners had come to pay their respects to the family of a southern separatist who died earlier in the week, the sources told Reuters.
The tent had been set up inside a school in the southern province of al-Dhalea by members of the al-Herak al-Janoubi, a coalition of groups aiming to set up an independent state in the region.
President Abd-Rabbu Mansour Hadi set up a committee to investigate the incident, state news agency SABA reported, without going into further details.
Unrest after ouster of president
Yemen is struggling to restore state authority after mass unrest ousted president Ali Abdullah Saleh a year ago.
Islamist militants strengthened their grip on parts of the country, before being pushed back by U.S.-supported military action - and southern groups stepped up their campaigns for separation.
Yemen's north and its once-Marxist south united in 1990, but civil war broke out four years later. Then-President Saleh crushed southern secessionists and maintained the union.
Elsewhere, two Islamist militants were killed in an air strike in east Yemen, residents and a local official said.
The strike hit a car carrying the militants in Hadramout province setting it on fire, they said.