SANAA (Reuters) - Armed tribesmen killed 18 Houthi fighters in an ambush in Yemen's central province of Ibb on Tuesday, residents said, in one of the deadliest ground attacks in over two months of war.
The attack hit a convoy of militiamen and allied army troops in the town of Qaeda while they were en route to the city of Taiz, a flashpoint of clashes between Yemen's dominant Houthis and armed backers of exiled president Abd-Rabbu Mansour Hadi.
Farther south in Dhalea province, around 15 Houthi fighters were killed in heavy clashes with pro-Hadi fighters on Monday night.
A coalition of Arab countries led by Saudi Arabia, seeking to restore Hadi to power, has carried out over nine weeks of air strikes on Houthi fighters who have seized large parts of Yemen.
The Houthis, members of a Shi'ite sect hailing from a Yemen's far north, seized the capital in September and fanned out southward, triggering the Arab military intervention.
They describe their spread as a revolution and a victory against corruption, but Sunni Muslim Gulf Arab states worry that they are a proxy for the influence of their regional Shi'ite rival Iran.
Saudi-led air strikes hit Houthi positions along Yemen's far northern border with the kingdom and struck military bases aligned with the group in the capital Sanaa on Tuesday.
Residents of Yemen's far northern province of al-Jawf said five suspected al Qaeda members were killed in a suspected American drone strike on two cars in a frontline battle area between the Houthis and Sunni tribesmen.
The United States fears that the political chaos in Yemen could strengthen Al Qaeda in the Arabian Peninsula, the deadliest branch of the global militant group. It has kept up its aerial bombings on the group's operatives.
As the Houthis and their army allies have spread into some majority Sunni areas in Yemen, local tribesmen have in some cases joined forces with al Qaeda militants, bolstering the group's influence in local affairs.
Neighboring Oman, a neutral power, is mediating talks between Houthi and American officials in the capital Muscat aimed at ending Yemen's conflict.
The dialogue also led Yemeni authorities to release to Oman on Monday a detained American freelance journalist.
Yemeni politicians say the discussions are narrowing ground between Yemen's exiled government and the Houthis and may soon pave the way for more formal United Nations-backed negotiations.
(Reporting by Mohammed Ghobari in Sanaa and Noah Browning in Dubai; Editing by Dominic Evans)