Thousands of Yemenis who back southern secession demonstrated in second city Aden on Sunday as a self-proclaimed autonomous body said it would press for the south's "liberation" from the north.

The protest was the second since 4 May when thousands of southerners marched in support of former Aden governor Aidarous al-Zubaidi after he was sacked by President Abd Rabbuh Mansour Hadi.

After being fired in April, Zubaidi set up the South Transition Council, an autonomous body whose 26 members include the governors of five southern provinces and two government ministers.

The body chaired by Zubaidi aims to "run the southern provinces" and "represent them inside and outside" the country.

The presidency in war-ravaged Yemen has rejected the body and said in a statement last week that "such acts remain baseless and will never be accepted".

The port city of Aden is Hadi's hometown and where his government, which is battling Shia Houthi rebels who have seized the capital Sanaa, is based.

Sunday's protesters, who flooded Aden from several southern provinces, defended Zubaidi's council, chanting "Independence is our objective" as they marched.

The South Transition Council released a statement pledging to "pursue the mission of liberating" south Yemen, which was an independent state until 1990 when it was unified with North Yemen.

Hadi sacked Zubaidi on 27 April along with cabinet minister Hani bin Breik, in a move widely seen as reflecting divisions among his supporters.

The two men played key roles in restoring security to Aden and adjacent provinces after rebels were pushed out in 2015.