Sana’a: Al Houthi militants who have toppled Yemen’s government are threatening to take over a key oil-producing province to the east of the capital, triggering fears that the country could explode in all-out civil war.

The rebels, have already seized much of the country’s north with relative ease. But they are likely to encounter stiff resistance if they move into Marib province. Already, the largely Sunni tribes in the region are arming themselves with tanks and rocket-propelled grenades, according to tribal leaders, and the governor has ringed the area with tribal fighters and military units.

“It will be civil war if they come here,” said Mohammad Al Wills, a leader of the Murad tribe in Marib, who has begun coordinating with fellow tribesmen and soldiers to defend the province.

Al Houthis say they want to protect residents of Marib from Al Qaida in the Arabian Peninsula (AQAP), whose fighters have launched periodic attacks in the province. But diplomats and analysts say a conflict could wind up strengthening Yemen’s franchise of Al Qaida, which has plotted high-profile attacks on the United States. A battle could also draw in tribesmen and Sunni fighters from other provinces.

Many Yemenis believe that Al Houthi rebels are backed by Iran. Now Al Houthi officials and Western diplomats say, Saudi Arabia is providing cash to Marib residents to arm themselves for a confrontation.

“This is becoming a sectarian-driven war because of these outside powers,” said Ali Saif Hassan, a Yemeni political analyst.

Al Houthis swept into Sana’a in the fall and effectively forced out the pro-US government of President Abd Rabbo Mansour Hadi in January. The rebels recently seized a military base on the way to Marib, and they have taken over parts of the province to its south, heightening speculation that they might soon move on to the important oil-producing province.

Marib is a strategic prize. Yemen is a small petroleum producer compared with some of its neighbors. But the national government’s budget is overwhelmingly dependent on oil sales. Marib is also home to power plants that provide electricity to Sana’a and other areas of the country, giving whoever controls the province a chokehold over Yemen’s energy supply.

“Everybody’s bracing for a clash there. It’s about the resources,” said a Western diplomat who until recently was based in Yemen, speaking on condition of anonymity.

The governor of Marib, Sultan Al Arada, said in a telephone interview that Al Houthis had carried out an Iranian-backed “coup” against the Yemeni government. He said his office is coordinating the defense of the province and its oil installations with local tribes as well as military units that are not loyal to Al Houthis. He denied that the Saudis were pouring money into the area to parry a rebel advance.

Tribesmen from neighboring regions have pledged to help the province hold off Al Houthis, he said.

“We have thousands of people from the tribes forming a security belt on the edges of the province, and the military is coordinating with us and preparing to defend us, too,” he said.

Al Houthis have called on Arada to step down. Last month, before forcing the resignation of the national government, the insurgents’ leader, Abdul Malik Al Houthi, warned that his fighters could intervene in Marib. He said the potential operation might be necessary to fight Al Qaida and “support the honorable people of Marib.”

Located about 75 miles east of the capital, Marib is poor even by Yemeni standards. The government in Sana’a has long been accused by residents of taking the area’s resources but offering few public services in return. In the political void created by the government’s collapse, the role of the area’s already powerful tribes appears to have been strengthened.

Hussein Hazeb, 50, another leader of the Murad tribe, said that tribesmen in the Marib area had armed themselves in part by seizing weapons from a military unit that recently passed through the province.

Some tribal leaders have long received financial support from Riyadh, the Saudi capital, he said, but the recent influxes of cash have been noticeably large.

“All of a sudden you’re seeing people with brand-new pickup trucks and new guns, and you know that they’re getting this from Saudi (Arabia),” Hazeb said.

An official at the Saudi Embassy in Sana’a declined last week to comment on the issue. The embassy closed its operations in Yemen on Friday.

Al Houthi officials also say that cash is being smuggled from the Saudi border to Marib. Al Houthis deny that they are backed by Iran.

Analysts, diplomats and many Yemenis fear that the escalating violence could strengthen Al Qaida’s franchise here by enabling it to portray itself as a champion of the Sunnis. Already, AQAP fighters may be moving from other parts of Yemen into Marib in advance of a fight, diplomats and analysts say.

On Thursday, Al Qaida militants seized a military base about 60 miles from Marib in a southern province, saying that they wanted to protect it from Al Houthi attacks.

In Marib, some tribes have fought AQAP, but the extremist group’s sectarian rhetoric appears to be resonating even among those Sunnis who have been its enemies.

Al Houthis “are Shiites and they reject Islam,” said Hamed Wahaed, a Marib tribal leader. He has been storing weapons in preparation for an Al Houthi assault; he boasted by telephone that he owns 10 Toyota pickup trucks mounted with machine guns, two artillery pieces, and rocket-propelled grenades.

He added that Marib has “to fight the Shiite-Iranian terrorists.” Still, he said he opposed Al Qaida and wouldn’t accept its support.

Some tribal officials have threatened to blow up power lines and oil installations in the province to deter an Al Houthi attack. That would be a serious blow to Yemen’s already weak economy.

“There is no doubt that such an attack on the oil and gas pipelines, as well as on the power plant, will cause a huge crisis for Yemen,” said Hassan Thabet, a professor of economics at Sana’a University.

Al Wills, the tribal leader, said he opposes damaging the oil and power lines, but he described the threats as a last-resort measure against Al Houthis.

“Some of the tribes see this as something like, ‘You may try to take us down, but we’ll take down the whole country if you try,’ “ he said.