Yemeni government forces and rebels were engaged in fierce fighting as a 48-hour ceasefire declared by the pro-government Arab coalition ended Monday, military officials said.
Fifteen rebels and nine loyalist troops were killed in clashes overnight in and around the flashpoint southwestern city of Taez, military and medical sources said.
Four civilians were killed and 11 others wounded in rebel bombing of loyalist-held neighbourhoods, the sources said.
Early Monday, forces loyal to President Abedrabbo Mansour Hadi attacked Shiite Huthi rebels and their allies on the western outskirts of Taez, military officials said.
The offensive, coming hours before the midday (0900 GMT) scheduled end of the ceasefire, targeted an air defence base, the officials said, while witnesses reported loud explosions.
Four of the Huthi casualties were killed in an air strike by the Saudi-led coalition, which has been fighting the rebels since March 2015, when insurgents expanded their control and forced Hadi into exile.
Coalition warplanes have also hit rebel positions in Nahm, north of rebel-held capital Sanaa, and in the Huthi's heartland in Saada province, witnesses said.
Warplanes from the coalition also conducted numerous sorties over Sanaa early Monday.
Elsewhere, pro-Hadi forces said they repelled a rebel attack on their positions in Sarwah, in Marib province, east of the capital.
The ceasefire began on Saturday following an intervention by US Secretary of State John Kerry who met Huthi rebel representatives in Oman and urged Hadi's government to sign up.
Coalition spokesman Major General Ahmed Assiri said the truce could be extended if there was a "complete halt to the violations" he attributed to the rebels.
He accused the rebels of 180 violations in the first 10 hours of the truce.
A spokesman for renegade Yemeni troops allied with the rebels accused the other side of forces more than 100 violations of the ceasefire.
Yemen's devastating conflict erupted in 2014 when the rebels overran Sanaa and other parts of the impoverished Arabian Peninsula country.
The United Nations says more than 7,000 people have been killed and nearly 37,000 wounded in Yemen since March 2015, when the coalition intervened on behalf of the government.
Source: National News Agency.