Crisis talks, aimed at ending the ongoing political tensions and escalating violence in Yemen, would be open to the Houthis, Qatar's Foreign Minister Khalid al-Attiyah said on Thursday.

It had previously been unclear whether the Houthis would be invited, despite their militias holding sway over most of northern Yemen, as well as the capital Sanaa.

According to Attiyah, the six Sunni-dominated Gulf Cooperation Council members agreed to that request last Monday but have not set a date for the meeting.

"The invitation concerns the Houthis," Attiyah, whose country currently holds the GCC's rotating presidency, told reporters following a meeting of Gulf foreign ministers in the Saudi capital Riyadh.

"It's their business to accept or not."

GCC Secretary General Abdullatif al-Zayani confirmed that "the invitation was addressed to all" protagonists in the crisis in Yemen, which is a frontline in the United States war against al-Qaeda.

The Houthis helped to spark the latest crisis earlier this year when their militias stormed the Presidential Palace and put President Abd-Rabbuh Mansour Hadi under effectual house arrest. Hadi then resigned, seemingly due to Houthi pressure, and was able to escape in February and flee south to Aden where he reneged his resignation.

The GCC has labelled the incident a coup by the Houthis and called for Hadi to be reinstated. The UN has been trying to broker talks, although attempts to date have been largely stillborn.

While Hadi insists that the talks cannot take place in Sanaa, where he claims the Houthis can unduly influence deliberations, and has suggested that the talks be moved to Saudi Arabia, the Houthis have so far opposed any change in venue. Saleh's General People's Congress party has also warned that it will boycott talks held outside Sanaa. Saleh is widely accused of backing the Houthis.

The talks, aimed at resuming the political process, begun after the departure of former president Ali Abdullah Saleh in early 2012, and collapsed after Western-backed Hadi fled the capital.

The Houthis oppose the process and insist that its proposals to turn the republic into a federation of six regions, would divide the country into rich and poor areas.

The Houthis stunned many observers last year when they made lightning advances in northern Yemen, prompting speculation they were receiving support from Saleh as well as Iran. In September, they were able to stage large-scale protests in the capital in September 2014 that eventually forced Hadi to fire the prime minister.

Since then they have continued to make inroads into the west and south, although they have begun to encounter firmer resistance from local tribes as well as al-Qaeda.

On Thursday, a leading Houthi member reportedly said the Shiite group was planning to conduct its first "military maneuvers" near the Saudi border.

"The maneuvers are meant to send a clear message to whoever seeks to meddle with the country's security, be they domestic or foreign," the group member, requesting anonymity, told The Anadolu Agency.

But the GCC insisted it was prepared to fight off any attacks, with the GCC insisting they could hold off any attack.

"GCC countries are capable of defending their interests and borders," Attiyah told reporters.