Yemen's prime minister on Monday flew back to the southern city of Aden under the terms of a peace deal with southern separatists who had expelled the government from its provisional capital in August.

The return from Riyadh of Prime Minister Maeen Abdulmalik Saeed and four other ministers, initially planned for last week but delayed for logistical reasons, follows the November deal with separatists.

Fighters of the separatist Southern Transitional Council (STC) last August seized control of Aden, which had become the seat of government after it was driven out of Yemen's capital Sanaa in 2014 by Houthi rebels.

The STC and the government, which are technically allies in the fight against the Houthis, inked a power-sharing deal in Riyadh on November 5 under Saudi mediation.

As well as heralding the government's return to Aden, it laid the foundation for forming a new 24-member cabinet with equal representation for southerners, including the STC.