More than 40 people were killed on Tuesday after renewed clashes between Yemeni government and the Houthi rebels, military officials said.
Clashes occurred a day after the expiry of a fragile 48-hour ceasefire.
Both the parties have traded blame over violations of the ceasefire which came into effect on Saturday after US Secretary of State John Kerry intervened. It was the latest international attempt to end Yemen's 20-month conflict, which the United Nations says has killed more than 7,000 people and wounded nearly 37,000.
Forces loyal to Saudi Arabia-backed President Abd-Rabbu Mansour Hadi repelled an attack by Iran-supported Huthi rebels and their allies on the western outskirts of Taiz city, the officials said.
The situation in Taiz is alarming. More details in our news release; https://t.co/GALlB5mZgU— ICRC Yemen (@ICRC_ye) November 22, 2016
The attack that began late Monday targeted the Al-Dhabab area, which provides pro-Hadi forces with their only access to the flashpoint city of 300,000 people that is surrounded by rebels.
Warplanes from the Saudi-led Arab coalition took part in operations to repel the attack, officials said.
Military officials also reported heavy artillery fire in an eastern suburb of Taez as pro-Hadi forces pressed a campaign to wrest back control of a presidential palace, police headquarters and an air defence base from the Huthis.
Eleven rebel fighters and five pro-government soldiers were killed in the clashes around the southwestern city, they said.
In northwest Yemen, fighting around the coastal town of Midi cost the lives of 18 rebels and four soldiers, a loyalist commander on the ground, Abdel Ghani Chebli, said.
Rebel sniper fire on Monday night killed three soldiers as the Huthis tried to advance on Midi's harbour, which is controlled by pro-Hadi forces.
In the Saudi border town of Najran, a Yemeni civilian was killed and seven other non-Saudis were wounded by rebel shelling from Yemen, the Saudi civil defence said.
Cross-border fire from Yemen has killed dozens of people in Saudi Arabia since March 2015.
The Huthis overran the capital Sanaa and other parts of the impoverished country in September 2014, prompting the coalition to intervene six months later in support of Hadi.