Yemeni President Abedrabbo Mansour Hadi accused Shia rebels and their allies on Tuesday of dashing hopes for peace after they unveiled a new government in areas under their control.
Hadi said that Monday's formation by the Iran-backed rebels of a government of national salvation showed their determination to "spread chaos and destruction" and "destroys any chance of dialogue and peace".
Speaking through a spokesman from Yemen's second city Aden, the seat of his beleaguered government, Hadi called on the international community to "condemn this move and hold the militia responsible for the collapse of peace efforts."
Announcing their new government, the Houthi rebels said it was a response to Hadi's "stubbornness" in pursuing a deadly war against them with the support of a Saudi-led coalition since March last year.
The war of words comes as the UN envoy for Yemen shuttles between the two sides in an effort to revive a US-backed ceasefire that collapsed after just 48 hours early last week.
Ismail Ould Cheikh Ahmed, who has been attempting to persuade the two sides to agree to a government of national unity, met rebel representatives in Oman on Saturday and is scheduled to hold talks with Hadi in Aden.
The president, who is usually based in neighbouring Saudi Arabia, flew into Aden on Saturday on his first visit in a year.
Fierce fighting has raged on the ground since the ceasefire collapsed.
The rebels launched an attack on loyalist positions in Dhaleh province north of Aden on Tuesday but were repulsed, a military official said.
Three government troops and 14 rebels were killed.
Witness Fawaz al-Marissi said the insurgents had been forced to leave their dead behind in the rough terrain.
Despite 20 months of Saudi-led military support, Hadi's authority is still largely confined to the south and areas along the Saudi border. The rebels control the capital Sanaa and most of the north.
The conflict has claimed more than 7,000 lives and left millions of civilians dependent on food aid.