Thousands of Yemenis demanding secession rallied in the streets of Aden on Friday, waving the flag of the formerly independent south in their third protest since May.

Protesters marched through central Aden, Yemen's second city and home to the war-ravaged country's government.

They chanted their support for the South Transitional Council and demanded the independence of south Yemen, which was an independent state until 1990, when it was unified with north Yemen.

The South Transition Council, an autonomous body aimed at overseeing self-governance among southern provinces, was declared in May. It is not recognised by the government of President Abd Rabbuh Mansour Hadi.

The 26-member council includes the governors of five southern provinces and two cabinet ministers.

Aden serves as a temporary base for the Hadi government, as the capital Sanaa has been held by Huthi rebels since September 2014.

Hadi is himself based in Riyadh, having fled Aden in March 2015 as the Shia rebels closed in on his refuge. 

In May, tens of thousands of Yemenis protested in Aden against Hadi's sacking of the provincial governor and a cabinet minister widely praised for helping drive Iran-aligned Houthis from the city in 2015.

The two men sacked, Aden provincial governor Aydaroos al-Zubaidi and cabinet member Hani bin Brek, are both seen as supporting separatism for southern Yemen, while Hadi is determined to tighten his grip over a unified country.

Zubaidi was one of the leaders of the Southern Resistance, which helped to expel the Houthis from his city.

Zubaidi and Brek are also seen as close to the UAE, a powerful regional military player involved in a Saudi-led campaign that has waged war on Yemen.

More than 8,000 people have been killed in the past two years and tens of thousands wounded in the war in Yemen, according to the World Health Organization.

Diplomats and some analysts say Hadi is uncomfortable that among the forces trained and supported by the UAE are some pro-secessionist fighters.