Yemen's southern separatists have suspended their participation in consultations on a power-sharing deal for the south, known as the "Riyadh agreement," a Southern Transitional Council (STC) statement said on Tuesday.

STC's vice-president Hani Ben Brik said on Twitter that the suspension of negotiations by the STC was in protest at "irresponsible behavior by parties" towards the Riyadh agreement and was necessary to push for full commitment to the agreement.

The STC gave several reasons for withdrawing, including the collapse of public services in the south and military escalation by government forces in Abyan province.

"We renew our full commitment to what was agreed upon without any violations," he said.

The government and the separatist STC are the main Yemeni forces in a Saudi-led coalition fighting the Iran-aligned Houthi movement, which drove the government out of capital Sanaa five years ago.

The Yemeni allies have been in a standoff since last August when the STC took over Aden, the temporary headquarters of the government.

The Riyadh agreement suffered many setbacks and was never implemented, but Saudi made a new push in July to invigorate the process.

Last month, the UAE-backed STC said they rescinded their demands for self-rule and pledged to implement a power-sharing deal, which was brokered by Saudi Arabia in November last year but was never implemented.

Yemen's war has driven millions of people to the verge of starvation, requiring the world's biggest humanitarian response.

The dispute within the anti-Houthi camp has been holding up UN efforts to negotiate a ceasefire in the wider conflict.

(With input from Reuters)