Saudi-backed Yemeni troops and their allies clashed with Shiite Houthi rebels in a strategic town north of the port city of Aden Sunday, security and military officials from both sides of the conflict said.

The pro-government fighters had withdrawn from the town of Sabr earlier in the day after fierce battles with Shiite Houthi rebels. They returned hours later following the arrival of military reinforcements and wrested control of a large portion of the town, security officials said.

The officials said five pro-government fighters were killed and 15 wounded in the battle. Local medical officials said eight rebels were killed and 20 wounded.

The running battles in Sabr, which is on a key supply route, have lasted for more than a day after troops stormed it in their push north from Aden toward the strategic military base of Al-Anad, which is held by the rebels.

The fighting came hours before the start of a five-day humanitarian pause announced by the Saudi-led coalition.

"If the Houthis and their allies do not stop fighting, we will continue to fight," said an official allied with the Saudi coalition.

The rebels, known as Houthis, have expressed doubt over the truce, which is set to begin Sunday just before midnight. One Houthi official said it will likely mark "the beginning of a new war."

The Saudi-led and U.S.-backed coalition of mainly Gulf Arab countries has been waging an air campaign since March against the Iran-supported rebels, who control most of northern Yemen and the capital, Sanaa.

The Houthi media office said fierce battles are also taking place near Dar Saad, a town outside of Aden.

Coalition force launched dozens of airstrikes in the areas surrounding Sabr, Dar Saad and Al-Anad in the hours leading up to the cease-fire, security officials said.

The Yemeni troops fighting in Sabr had been training since April in military camps in al-Buraiqeh, the port city west of Aden, military officials from the Saudi-led coalition said. Saudi, Emirati, Egyptian and Jordanian military advisers there have set up the camps and trained hundreds of fighters, they added.

The fighters also received over 300 armored personnel carriers from the United Arab Emirates by sea. These sophisticated carriers are largely driven by non-Yemenis, the military officials said. Two Emirati officers have been killed in battle in Yemen since the Saudi-led coalition's latest offensive, known as the "Golden Arrow," started on July 16.

Al-Buraiqeh is also home to the Yemeni Fourth Military Base, which is in charge of all military operations in Aden.

The foreign military advisers, officials said, arrived in al-Buraiqeh by sea more than a month ago and serve as intermediaries between the Yemeni troops and the coalition leadership in neighboring Saudi Arabia. They also supervise the distribution of weapons and give coordinates for coalition airstrikes, military officials said.

All the officials spoke anonymously because they are not authorized to brief reporters.