Security forces clashed with protesters in several cities across Yemen at the weekend, leaving at least four people dead and dozens injured.
Tens of thousands of people rallied on Saturday to mark the 18th anniversary of the capture of the port of Aden by forces loyal to ex-president Ali Abdullah Saleh during the country's brief civil war.
Troops in Aden blamed protesters for shooting first and said they had merely returned fire. At least three marchers were killed.
Another protester was killed at a demonstration in Sayoun, while soldiers in Mukalla were accused of firing on a march.
Rallies in southern cities demanded "freedom and independence" and posters read: "Investigate the crimes of 1994 and return stolen property."
The former socialist state of South Yemen merged with the North in 1990, but civil war broke out following claims that the south had been marginalised and discriminated against.
Fire Minister Brandon Lewis probably had a fair idea what Sir Ken Knight would deliver when he asked him to conduct an "independent" report into fire and rescue services in England.