Shia Houthi rebels on Tuesday captured a key port city in western Yemen, extending their gains in the country where they already control the capital city of Sanaa, according to media reports. The Houthi rebels reportedly met with little or no resistance from security forces in the city.

The rebels have set up checkpoints after taking over several military bases in Hodeida, a city with a population of more than two million located about 125 miles west of Sanaa, according to media reports. The Shia rebels, who are believed to be supported by Iran, also took control of Damar province and its provincial capital, also called Damar, south of Sanaa.

“Houthi militants are deployed across vital installations, including the airport and the port,” a security official in Hodeida said, according to local media reports.

The newly captured territories are significant additions to the regions already under rebel control, which include Sanaa -- where they have remained unchallenged since seizing control on Sept. 21 -- and the provinces of Saada and Omran north of the capital.

The new rebel onslaught comes just a day after President Abed Rabbo Mansour Hadi appointed Khaled Bahah, Yemen’s envoy to the United Nations, as the prime minister. The Houthis had reportedly approved of Bahah’s appointment, calling him the “right person” to lead the conflict-ridden country.  

Hadi, who reportedly has the support of the U.N. and the U.S., has been facing sectarian challenges from Shia Houthis as well as hardline Sunni Muslims, including al Qaeda, which has carried out a series of bombings in the country in recent weeks.

The Houthis, who are a Zaidi Shia group constituting nearly 30 percent of Yemen's population, have been trying to enlarge their zone of influence since January by capturing territories in the country’s north and south.