Shia rebels have rejected a new Yemeni prime minister just hours after his appointment, in a blow to hopes of restoring order two weeks after they overran the capital.

President Abd Rabbu Mansour Hadi appointed his chief of staff, Ahmed Awad bin Mubarak, as the country's new premier on Tuesday.

Houthi rebels told Al Jazeera they rejected the new prime minister as no agreement officially took place.

"We strongly reject this nomination, which is not in accord with the will of the nation and does not respond to the wishes of the people," the rebels said in a statement after the appointment.

"This appointment is at the behest of outside forces, a denial of national sovereignty and... the rule of consensus that must direct the process of political transition," the statement added, without elaborating.

The rebels refusal will further delay the implementation of a ceasefire deal sponsored by the United Nations that called for the Houthis to withdraw from Sanaa once a new neutral prime minister was named.

Houthi fighters stormed into Sanaa in an offensive on September 21 and proceeded to establish a strong military presence, mounting patrols and manning checkpoints.

The rebels have refused to withdraw from the city so far despite the UN deal promising them more influence with the Sunni-dominated government.

Born in the southern port of Aden, bin Mubarak was one of the representatives in the dialogue of the Southern Movement, which seeks autonomy or secession for the formerly independent south. He was also secretary general of the national dialogue on Yemen's political transition.

The Houthis are now believed to be trying to expand their influence eastwards to the country's main oilfields and southwest toward the Red Sea.

Source: Al Jazeera and agencies