Saudi-led coalition forces advanced on Monday towards Yemen's third city Taez after sending major reinforcements in a bid to break a months-long siege by Iran-backed rebels, military officials said.
The move comes ahead of an expected offensive to retake the city, seen as a gateway to controlling the rebel-held capital, said the Yemeni officials.
Armored demining vehicles and other reinforcements arrived in the Shuraija region, between the loyalist-controlled Lahj province and Taez in the southwest, said officials in the main southern city of Aden.
Sudanese forces from the strategic Al-Anad airbase in Lahj are taking part in the Taez operations, according to the sources.
Taez has seen heavy fighting in recent months between the Shi'ite Houthi rebels and forces loyal to President Abedrabbo Mansour Hadi's internationally recognized government.
Loyalist forces are inside Taez, while the rebels and troops loyal to former president Ali Abdullah Saleh control the main roads leading into the city.
Along the coast, coalition troops deployed in Dhubab in a bid to advance onto the Red sea city of Mocha, a part of Taez province which is under rebel control, the sources said.
On Sunday, military officials spoke of major coalition reinforcements of troops and equipment arriving to Taez from Aden.
Meanwhile, three pro-government fighters and two rebels were killed in clashes an area on the border between Taez and Lahj, military officials said, adding that loyalists managed to retake a hill overlooking the area.
This month, a 400-strong Sudanese force arrived in Aden in support of loyalist forces, joining 500 who arrived last month.
Some 5,000 people have been killed in the conflict since March, more than half of them civilians, according to the United Nations.
A new round of UN-brokered Yemen talks to end the conflict is expected to kick off in Geneva this month.
