* "A stomach-churning development" - Amnesty
* Health services already affected - ICRC
* Yemen appoints new defence minister
ADEN, Nov 8 (Reuters) - Houthi fighters battled Saudi-led forces in Yemen's port city of Hodeidah on Thursday and posted gunmen on the roof of a hospital, leaving doctors and young patients in the line of fire, rights groups and military sources said.
The Houthis raided the May 22 hospital in the city's eastern suburbs, sources said, as clashes raged on in the face of mounting calls from world powers, including some of Saudi Arabia's main Western allies, for a ceasefire.
"This is a stomach-churning development that could have devastating consequences for the hospital's medical workers and dozens of civilian patients, including many children," said Amnesty's International's Middle East Director of Campaigns, Samah Hadid.
Fighting was getting closer to the hospital and had already disrupted services there, the International Committee of the Red Cross added.
Houthi officials did not immediately respond to a Reuters request for comment.
A Saudi-led coalition has been battling to push Iran-allied Houthis out of the city they have held since 2014. A surge of fighting in the past week has trapped thousands of civilians in the crossfire and coalition air raids.
U.N. bodies and other powers have warned that an all-out attack on the city, an entry point for 80 percent of Yemen's food imports and aid relief, could trigger a famine in the impoverished state.
The latest fighting has focused on Hodeidah's eastern 7th July neighbourhoods and around a university just 4 km (2.5 miles) from the port and a few blocks from al-Thawra hospital, the main medical facility on Yemen's western coast.
NEW DEFENCE MINISTER
Saudi Arabia is leading a Western-backed alliance of Sunni Muslim Arab states to try to restore Yemeni President Abd-Rabbu Mansour Hadi and his internationally recognised government that was ousted from the capital Sanaa by the Houthis in 2015.
As fighting mounted overnight, Hadi appointed a new defence minister - Mohammed al-Maqdishi - and named Abdullah Al-Nakhi as Chief of Staff, state news agency SABA reported.
Maqdishi had been chief of staff and the facto defence minister for more than a year, and the official title would give him more authority to oversee the fighting, a senior Yemeni government official told Reuters.
Yemen's ousted govenrment has fled further south down the coast in Aden, but Hadi and other cabinet members are based in Riyadh.
The Houthis say they are defending their homeland from foreign invaders and accuse the Yemeni government of decades of marginalisation.
The United Nations has no up-to-date estimate of the death toll in Yemen. It said in August 2016 that according to medical centers at least 10,000 people had been killed.
Pressure has mounted on Saudi Arabia since the killing of Journalist Jamal Khashoggi in the Saudi consulate in Istanbul last month, to end the 3-1/2 year war that has already created one of the world's worse humanitarian crises.
Amnesty added it has documented a series of air strikes carried out by the Saudi Arabia and UAE-led Coalition in the lead-up to the recent escalation in fighting, including two that killed 11 and 21 civilians last month.
(Reporting by Mohammed Ghaobari; Additional reporting by Stephanie Nebehay in Geneva; Writing by Aziz El Yaakoubi; Editing by Andrew Heavens)
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