Saudi Arabia's crown prince called Wednesday for stronger military cooperation between the United States and the Arab monarchies of the Gulf whose security he said was under threat.

Crown Prince Salman bin Abdulaziz, who also holds the defence portfolio, made the remarks at a meeting in the Saudi city of Jeddah between US Defence Secretary Chuck Hagel and ministers from the six-nation Gulf Cooperation Council.

Hagel for his part stressed that Washington remained "committed" to the oil-rich region's security and stability.

"We meet today amid persistent threats to the region's security and stability," which "necessitate coordination in politics and defence strategies of our countries," said Prince Salman.

"The security of our countries and our people is in danger," he added.

The crown prince singled out concerns over "political crises" in some Arab states, as well as "attempts to acquire weapons of mass destruction and meddling of certain states" in the internal affairs of others, in an apparent reference to Iran.

He stressed that "historic and strategic relations" between Washington and GCC countries had "contributed to cementing security and stability in the region."

Hagel also called for cooperation in dealing with security threats.

"The security challenges facing this region threaten the region as a whole, and no one nation can address them alone," he said at the end of the meeting.

"We agreed on the need for more cooperation in three areas: more integrated air and missile defence coordination; closer maritime security integration; and expanded cybersecurity cooperation," he said.

US officials have struggled to reassure Gulf states, particularly Saudi Arabia, over an interim nuclear deal struck with Iran last year that Riyadh worries will embolden Tehran.

The GCC has also been dissatisfied with Washington's cautious approach to arming rebel forces in Syria.

Hagel said the Jeddah meeting underlined a shared commitment to "preventing Iran from obtaining a nuclear weapon - and ensuring that its programme is exclusively peaceful."

Despite Tehran's diplomatic engagement being a "positive development," Washington and Gulf states "continue to share "concerns about Iran's destabilising activities throughout the region."

This includes Iran's "sponsorship of terrorism, its support for the (President Bashar al-) Assad regime in Syria, and its efforts to undermine stability in GCC member nations," he said.

"That is why we are committed to continuing to work together to reinforce GCC defences and capabilities," he added.

On Syria, Hagel said the ministerial meeting agreed that assistance to the rebels "must be complementary," adding "it must be carefully directed to the moderate opposition."

The Pentagon said last week that Hagel aimed to "underscore US security commitments in the Middle East and to reinforce the United States' unstinting policy of preventing Iran from acquiring a nuclear weapon and further destabilising the region."

After his stop in Saudi Arabia, Hagel was to head to Amman for talks on the three-year-old conflict in neighbouring Jordan.