Houthi militants controlling Yemen’s capital are trying to build ties with Iran, Russia and China to offset Western and Saudi support for the country’s ousted president.

The Houthis’ interim government has sent delegations to Iran in search of fuel supplies and to Russia to look for investment in energy projects, according to two senior Houthi officials. Another delegation is planning to visit China in the coming weeks, they said.

The U.S., France, Turkey and Saudi Arabia were among at least a dozen countries that shut embassies in San’a after the Houthis seized control of the capital in January, leaving their movement isolated internationally.

Since then, President Abed Rabbo Mansour Hadi has fled to the southern port city of Aden, where he is appealing to his allies at home and abroad for financial and political support for an alternative administration. The U.S., the Sunni monarchies of the Gulf and the United Nations have sided with him.

The diplomatic standoff threatens to split the country and trigger a civil war fought along Yemen’s many sectarian, political and geographical fault-lines. The Houthis and Mr. Hadi are the main adversaries in the deepening crisis, but the presence of Yemen’s Sunni Muslim tribes—and the country’s potent al Qaeda offshoot, which Mr. Hadi has fought with U.S. backing—add a layer of complexity to the conflict.

Houthi leaders say their interim government is trying to gain legitimacy abroad.

“We are doing what any new power does, and that is to seek international alliances that can help balance the new face of Yemeni politics,” said Ahmed Bahri, political director for the pro-Houthi Haqq Party.

Yemen, the Arab world’s most impoverished nation, has been afflicted by political unrest since Arab Spring-inspired protests erupted in January 2011. Those protests forced the longtime president, Ali Abdullah Saleh, to cede power to Mr. Hadi a year later in a political deal brokered by its Gulf Arab neighbors.

The country’s latest political crisis began last year, when rebels of the Houthi movement, part of the Zaidi offshoot of Shiite Islam, moved to extend their control southward from their northern stronghold. Estimates suggest Houthis make up roughly 30% of Yemen’s 26 million people.

Houthi militants took over San’a in September and demanded a greater share of power. After a series of compromises and broken cease-fires, Mr. Hadi tendered his resignation in late January and was placed under house arrest. Houthis took control of the government two weeks later.

Mr. Hadi withdrew his resignation after escaping to Aden, 320 miles south of the capital. His bid to reclaim power has heightened tensions among Yemeni political parties and between Iran and Saudi Arabia. Mainly Shiite Iran has long provided political and financial support to the Houthis, while Saudi Arabia, the region’s most influential Sunni Muslim country stands behind Mr. Hadi.

Houthi officials said they have approached Iran, their main ally, and are expecting Tehran to send gasoline to offset supplies cut off by Saudi Arabia. The Houthis also want to replace electricity supplies generated by Western companies with Iranian-supplied generators, they said.

Investment ties with Iran appear to be deepening, too, after two Iranian commercial airlines agreed this month to operate direct flights between Iran and San’a, and Iran was invited to consider energy exploration in the provinces of Al Jawf and Saada, which border Saudi Arabia and are under Houthi control.

“We want Iranians to invest in Yemen and they have the capacity to do so,” a Houthi official said. “The regional or Western boycott of the Houthis won't keep our hands tied but only make us seek new investment options for new countries.”

Iranian officials couldn’t be reached for comment on the trade and investment overtures. An Iranian foreign ministry spokeswoman said Wednesday that Iran opposed foreign interference in Yemen, state-run media reported.

A Yemeni delegation led by pro-Houthi politicians visited Russian members of parliament late last week and discussed potential investments in Yemeni energy projects, according to Houthi leaders.

No deals have been struck, but Leonid Issaev, a Russian expert on Arab affairs who helped arrange the talks, called them a “very productive” attempt to restore Moscow’s relations with Yemen to the high level they enjoyed during the Soviet era. Since the Soviet Union collapsed, he said, they had become weak.

A push for alliances with China is expected soon.

Abdullah Shaban, a member of the Houthis’ Revolutionary Committee, said the stepped-up diplomacy was aimed at securing foreign investment. He played down the need for foreign political support, saying the Houthi government could survive without new allies.

“Yemen is rich with natural resources and an open country for investments,” he said. “We want to give them a stronger role in Yemen and a chance to improve the economic situation of both of our countries.”

Khaled Fattah, an expert on Yemen, said the Houthis’ diplomatic strategy takes its inspiration from another the Syrian regime of President Bashar al-Assad, another Iranian ally that has cultivated ties with Moscow and Beijing to lessen its international isolation and prevent its collapse.

“Reaching out Moscow and Beijing is an attempt at duplicating the success of the regime in securing Russian and Chinese support, which deterred direct Western intervention and cushioned the Syrian regime against international isolation and collapse,” he said.

Mr. Fattah added, however, that the Houthis were unlikely to enjoy similar results, since neither Russia nor China had major interests in Yemen.

Ali Al Jaradi, a senior official in the pro-Hadi Islah party, was also skeptical, saying the Houthis lacked sufficient political experience to win over Moscow and Beijing.