SANAA (Reuters) - Saudi-led coalition warplanes struck at Houthi militia positions in Yemen's capital Sanaa for a second day on Monday in support of ex-president Ali Abdullah Saleh, a former Houthi ally who has now renounced his alliance with the Iranian-backed group.
The Houthis claimed on Monday to have made steady gains over Saleh's forces after six days of heavy urban warfare in Sanaain which dozens of people have been killed.
But residents reported intense fighting overnight and into the morning, with families hunkered down their homes as explosions rocked the city. Coalition air strikes pounded Houthi positions in an apparent bid to shore up Saleh's forces, witnesses said.
At the United Nations, U.N. Secretary-General Antonio Guterres urged the warring parties to stop all ground and air assaults.
Guterres also called for the resumption of all commercial imports into Yemen, saying millions of children, women and men risk mass hunger, disease and death.
The Saudi-led air campaign, backed by U.S. and other Western arms and intelligence, has killed hundreds of civilians but has failed to win the coalition any major gains in the nearly three-year-old military campaign to restore Yemen's internationally recognized president, Abd-Rabbu Mansour Hadi, to power.
However, in a speech late on Sunday, Saleh formally annulled his alliance with the Houthis and pledged to step up his fight.
The re-alignment of Saleh's forces with the Saudis would mark a significant turn in a war which is part of a wider struggle between regional powers Saudi Arabia and Iran.
Saleh, who dominated Yemen's heavily armed tribal society for 33 years before quitting in the aftermath of the Arab Spring in 2011, and the Shi'ite Huothis had made common cause against Hadi loyalists.
But they vied for supremacy over the territory they ran together, including the capital, which the Houthis seized in September 2014, and their feud burst into open combat on Wednesday.
Houthi spokesman Mohammed Abdul Salam claimed significant gains in the battle for Sanaa on Monday.
"With the aid and approval of God, the security forces backed up by wide popular support were able last night to cleanse the areas in which the militias of treason and betrayal were deployed," he said in a statement.
The Houthi movement's TV channel al-Masirah and witnesses said their fighters had seized the downtown home of Saleh's nephew Tareq, an army general.
Residents said the warring sides traded heavy automatic and artillery fire as the Houthis advanced in the central Political District, which is a redoubt of Saleh and his family.
"We lived through days of terror. Houthi tanks have been firing and the shells were falling on our neighborhood," said Mohammed al-Madhaji, who lives in the frontline district.
"The fighting has been so violent we feel we could die at any moment. We can't get out of our homes."
Aid groups have said the combat has killed dozens of people, adding to the woes on one of the Arab world's poorest countries inflicted by a war in which at least 10,000 have died as hunger and disease spread.
Houthi media and political sources also reported that the Houthis also advanced toward Saleh's birthplace in a village outside the city where he maintains a fortified palace. His whereabouts were not immediately clear.
(Writing By Noah Browning, Editing by Angus MacSwan)