SANAA (Reuters) - Militiamen clashed with Yemen's dominant Houthi group inside the city of Ibb on Tuesday, residents said, in their latest significant advance into territory the Houthis had held unopposed for months.
The local tribal fighters advanced into the central city, home to around 200,000 people, from two surrounding rural areas and set up checkpoints at its entrances. Residents reached by phone reported hearing heavy gunfire.
Yemen has been torn by over four months of civil war between supporters of its exiled government and the Houthis, who hold the capital Sanaa and much of the north.
A Gulf Arab military alliance intervened in late March just as the Iran-allied Houthis entered the southern port of Aden and appeared poised to capture the last bastion of resistance to what they view as a revolution against corrupt officials.
The coalition is keen to repel perceived influence by arch-rival Iran on the Arabian Peninsula.
Yemen's government, driven into exile in Saudi Arabia, has been cheered by a series of important victories by southern fighters since Aden was retaken last month with the help of heavy Arab air strikes and weapons deliveries.
Clashes with Houthi forces also raged on Tuesday in the central provinces of al-Bayda and Shabwa, where local militiamen appeared to be gaining the upper hand backed by warplanes from Gulf states bombing from the air.
Exiled officials have pledged to gradually resume their presence on Yemeni soil, beginning from their newly-won base in the south.
Foreign diplomats have pleaded for a political solution to the fighting which has killed over 4,300 people and warned that war is devastating the impoverished country.
Peter Maurer, the President of the International Committee of the Red Cross said after a three-day visit to Yemen on Tuesday the country was "crumbling" and a U.N. investigator said sieges imposed by combatants were causing starvation.
Hilal Elver, United Nations special rapporteur on the right to food, warned that "deliberate starvation of civilians" caught in armed conflict might constitute a war crime.
(Reporting by Mohammed Ghobari and Stephanie Nebehay; Writing by Noah Browning; Editing by Andrew Roche)