By Lesley Wroughton
JEDDAH, Saudi Arabia (Reuters) - Secretary of State John Kerry met Saudi Arabia's King Salman and the country's powerful deputy crown prince Mohammed bin Salman on Thursday to discuss ways to end conflict in Yemen and resume peace talks between the warring sides.
Kerry arrived in Jeddah late on Wednesday from Nigeria for discussions with Saudi leaders and other Gulf Arab states and will also update them on U.S. meetings with Russia on military cooperation in Syria, a senior U.S. official said ahead of the talks.
Backing by Gulf Arab states for the Syria plan is vital because they wield influence over Syrian opposition groups fighting to topple President Bashar al-Assad. Russia and Iran support Assad.
The talks come as Syrian rebels backed by Turkish special forces, tanks and warplanes entered one of Islamic State's last strongholds on the Turkish-Syrian border, in Turkey's first major U.S.-backed incursion into its southern neighbor.
The State Department said Kerry will meet Russian counterpart Sergei Lavrov in Geneva on Friday to try to close a deal on military cooperation and intelligence sharing in Syria. It could see Assad's warplanes grounded, while Russian and U.S. forces coordinate strikes against Islamic State.
Kerry also joined foreign ministers from Saudi Arabia and the United Arab Emirates, as well as a British official, at the Royal Terminal near Jeddah to explore ways to end an 18-month Yemeni war that has killed about 6,500 people, half of them civilians.
A Saudi-led air campaign in Yemen in support of the government of President Abd-Rabbu Mansour Hadi against Iran-allied Houthis has come under increasing scrutiny for causing a large number of civilian casualties.
In Geneva, the U.N. human rights office said on Thursday that air strikes by the Saudi-led coalition are responsible for the largest part of the 3,799 civilians killed so far and it has committed other violations that may contravene international law.
A senior State Department official declined to elaborate on Kerry's proposals.
"The multilateral meeting on Yemen is designed to share ideas and initiatives for getting the political discussions back on track and trying to get a political solution," the official said. It would also address getting aid delivered.
The U.S. military has coordinated with the Saudi-led air campaign in Yemen, helping ensure Saudi access to precision-guided munitions. The Pentagon has also sent U.S. military lawyers to help train Saudi counterparts in ensuring the legality of coalition strikes.
But there has been growing concern in Washington that the Saudi campaign may have targeted civilian installations including hospitals.
Human rights groups have argued that U.S. forces may also be responsible under the rules of war for civilian casualties because of its support for the Saudi campaign.
Kerry "will raise our concerns about civilian casualties and damage to civilian targets inside Yemen," the U.S. official said, adding that he would press the Saudis to ensure air strikes were "discriminate and precise".
In his 30-minute meeting with King Salman, Kerry exchanged words with the 80-year-old monarch about his health. Speaking through a translator in the first public comments on recent surgery in the United States, he complained about his back.
"We're happy to see you in good form," Kerry said, before reporters were ushered from the room.
(Additional reporting by Stephanie Nebehay in Geneva, Editing by Ralph Boulton)