Sunni militia fighters in Yemen dealt a blow to Shi'ite Houthi rebels Monday, seizing key military sites in the southern city of Dhale.
The number of casualties is unclear. One report said dozens of rebels were killed and 70 wounded.
Meanwhile, there was no let up in the Saudi-led airstrikes Monday across Yemen and in the capital, Sana'a.
Some witnesses say a house belonging to Ahmed Saleh, son of former President Ali Abdullah Saleh, was destroyed. The former president is one of the main supporters of the Houthi rebels.
The outlook for peace in Yemen is dim, with the fighting and airstrikes continuing. Yemeni and United Nations officials say a peace conference scheduled for Thursday has been indefinitely postponed.
Yemeni President Abdu Rabu Mansour Hadi, who is in exile in Saudi Arabia, is demanding Houthi rebels abide by a Security Council resolution and withdraw from territory they seized before the talks can proceed.
U.N. Secretary-General Ban Ki-moon has urged both sides to talk without any preconditions.
The U.N. says violence in Yemen has killed more than 1,000 civilians and says it could spread elsewhere in the region.