Pro-government forces gather in near the city of Zabid in Yemen's Hodeidah province. AFP

Yemeni pro-government forces are massing for an offensive to liberate the rebel-held city Zabid in Hodeidah province.

The Yemeni Resistance Forces has sent thousands of trained fighters to participate in the operation, UAE state news agency Wam said.

Using advanced military equipment, the forces will attempt to liberate the historical city while avoiding casualties to civilians, who are being used as human shields by the Houthi rebels, Wam said.

A Unesco World Heritage Site, Zabid is considered a key point for Yemeni forces to advance deeper into rebel-held areas east of Hodeidah.

Yemeni forces backed by the Arab Coalition have already seized several areas of the province from the Iran-backed rebels, while an offensive to retake Hodeidah city and its vital port was suspended early this month to assist UN mediation efforts.

The UN special envoy for Yemen, Martin Griffiths, stepped up negotiations with the Yemeni government and the Iran-backed Houthi rebels after the offensive on Hodeidah city was launched in mid-June. Coalition and government forces recaptured Hodeidah's airport but operations were halted to allow Mr Griffiths to negotiate a peaceful handover of the city and the resumption of peace talks.

So far, the Houthis have offered only to hand over control of Hodeidah port to the UN.

Officers in the two main Yemeni forces involved in the Hodeidah offensive, the Amalikah Brigades and the Tihama Resistance, have told The National that the coalition had ordered them to gather their forces and summon soldiers back from leave in recent days.

The coalition itself has moved heavy reinforcements to the western front, including tanks and armoured vehicles, the officers said.