Jeddah, Saudi Arabia: US Secretary of State John Kerry was holding talks with his Gulf counterparts and a British minister in Saudi Arabia on Thursday on the conflicts in Yemen, Syria and Libya.

The coordination with Washington's major Middle East allies came on the eve of Syria talks in Geneva between Kerry and his Russian counterpart Sergei Lavrov.

After a 30-minute meeting with Saudi King Salman, Kerry was to focus on the conflict in Yemen with UN envoy Ismail Ould Cheikh Ahmed, Britain's Middle East undersecretary Tobias Ellwood, and his Saudi and United Arab Emirates (UAE) counterparts.

On Yemen, a senior State Department official said, Kerry wants "to share ideas and initiatives for getting the political discussions back on track and trying to get a political solution".

The aim is also to put in place mechanisms for delivering desperately needed humanitarian aid to the impoverished country neighbouring Saudi Arabia, he said.

"It's not either-or. We want to get humanitarian access better ensured and at the same time we need a ceasefire in place. They go hand in hand but you need a reduction in violence," the official said.

Riyadh heads an Arab coalition that began air raids in March 2015 and later sent in ground forces to support Yemen's internationally-recognised government after Iran-backed Shiite Huthi rebels and their allies overran much of the country.

As the civilian death toll climbs following the suspension of UN-brokered peace talks, the kingdom has faced rising criticism from human rights groups.

The United Nations on Thursday called for the creation of an independent international body to investigate an array of serious violations in Yemen.

In a new report, it laid out a long line of allegations of grave human rights abuses by all sides in Yemen's war which has left nearly 4,000 civilians dead.

Saudi-led coalition air strikes were suspected of causing around half of all civilian deaths, while attacks by groups affiliated with the rebels were blamed for around a quarter of the deaths, the report said.

Kerry's encounter with Salman followed a three-hour meeting overnight with the king's powerful son, Deputy Crown Prince and Defence Minister Mohammed bin Salman.

Saudi Arabia and other Arab states in the Gulf belong to a US-led military alliance battling the Islamic State (IS) jihadist group which has seized large parts of Syria and Iraq.

The kingdom also backs armed rebels fighting Syrian President Bashar al-Assad's regime.

- Libya's GNA also on agenda -

Kerry was to update regional allies on efforts to end the heavy bloodshed in Syria "because they do have influence" over opposition groups, the State Department official said.

The secretary of state was due to head later Thursday for Geneva to meet Lavrov.

Moscow and Washington are on opposite sides of the five-year-old Syria conflict but have a common foe in IS, and they have been in contact on efforts to establish military cooperation against the jihadists.

IS has also claimed deadly bombing and shooting attacks against the Shiite minority in Saudi Arabia and its security forces.

The State Department official said earlier that Kerry's talks with the Saudis would likewise cover Libya, where a UN-backed Government of National Accord is challenged by a rival adminstration.

Pro-GNA forces are battling IS in Libya's coastal city of Sirte.

"What we're trying to do is to continue to support the GNA, work towards political solutions and making sure we're putting pressure on Daesh (IS) inside Libya," the official said.

Kerry was to focus on the same conflicts at a working lunch with ministers of the six-nation Gulf Cooperation Council which groups Saudi Arabia with its neighbours.

The talks came after their regional rival Iran sent four warships close to two US Navy guided missile destroyers in the Strait of Hormuz, according to American defence officials.

The USS Nitze shot warning flares, sounded its whistles and attempted unsuccessfully to communicate with the Iranian boats during Tuesday's incident, the US Central Command said.

The encounter occurred in international waters of the strait, a vitally important chokepoint into the Gulf with Iran on one side and the UAE on the other.