An Iranian airplane delivered supplies to Yemen's Shiite rebel-held capital on Sunday, while the president gained support from influential tribal and provincial leaders in signs that the rival camps seeking to rule the rapidly unravelling country are entrenching their positions.

The first direct flight from Shiite powerhouse Iran to Sanaa was carrying 12 tons of medical supplies as well as tents and and Red Crescent aid workers, Iran's deputy ambassador Rasai Ebadi told The Associated Press. It came a day after rebel Houthi representatives signed an agreement in Tehran to set up 14 direct weekly flights between the two countries.

The move underscored how the rebels, who are widely suspected of being backed by Iran, are strengthening their grip over state institutions and exercising sovereign power in Sanaa even as the country's president insists he is still in charge after fleeing to the south.

"The Houthis want to show they're not disconnected from the world, that they are not desperate, so they're reviving relations with Iran," said Yemen analyst Hisham al-Omeisy.

"The flights are a bit peculiar and people are surprised. Yemenis don't usually fly to Iran, for tourism or work or medical treatment, so 14 weekly flights seems like a bit too much. The point of the medical supplies was to kill the rumor that more weapons will be coming in to support the Houthis," he added.

Western embassies shut down and evacuated staff from Sanaa last month after the rebels stormed the presidential palace and placed President Abed Rabbo Mansour Hadi and his Cabinet ministers under house arrest. Hadi, who still claims to be the country's ruler, later managed to flee to the southern city of Aden.

While Russia, China, Iran and Oman have kept their embassies operating in Sanaa, Saudi Arabia, Kuwait, the United Arab Emirates and Bahrain have moved theirs to Aden. On Sunday, Qatar too said it would open its embassy there.

Hadi received local officials in Aden Sunday, along with influential tribal leaders and elders from the provinces of Jawf, Marib and Bayda, who assured him of their backing, local television stations reported, adding that Hadi again accused the Houthis of launching a coup against Yemen's legitimate leadership.

Meanwhile state news agency SABA, controlled by the Houthis, said the rebels' new governing council sent a delegation to Tehran Sunday for several days. Saleh al-Samad, a former Hadi adviser who headed the delegation, said the group would discuss furthering economic and political cooperation.

"Relations between Yemen and Iran were brotherly and positive but suffered under previous governments which were influenced by countries leading to a negative impact of relations with Iran," he said in comments carried by SABA.

In Sanaa, Yemeni airport, security and transportation officials greeted the Iranian Mahan Air flight, an Airbus 310, which the Iranians say will be followed by further humanitarian aid.

Analyst al-Omeisy said that with Hadi and the Houthis on a collision course, suspicion of weapons shipments via the Iranian flights will be high.

"They're headed for a showdown — the Houthis know it and so do the Iranians. There's a lot of speculation that the flights could eventually contain material other than medical supplies," he said.

"In any case, the Houthis control the airport so in the end nobody knows or will know what exactly is passing through," he added.