Thousands of Yemenis protested against a new peace proposal to end the conflict submitted by the UN envoy to the war-torn country, saying the plan would legitimise the rebels' power grab.

The demonstrations in the southern city of Aden and other locations took place on Thursday shortly before UN envoy Ismail Ould Cheikh Ahmed arrived in the capital Sanaa for peace talks with Houthi rebels.

"We reject the plan of Ould Cheikh," read one of the banners carried by protesters in Aden - the government's temporary base - who responded to a call by authorities in the city to rally. 

"No to an initiative that legitimises the coup," said another.

President Abd-Rabbu Mansour Hadi on Saturday rejected the envoy's peace plan, saying it would reward the Houthis for seizing the capital and "opens a door towards more suffering and war".

Hadi enjoys the backing of a Saudi-led Arab coalition that launched a military campaign in March 2015 after the rebels closed in on his refuge in Aden.