Photo: Mohammed Houthi, a top official in the Houthi group's military wing, attends a Houthi rally at the main stadium in Sanaa on Saturday. | REUTERS

SANAA – A day after taking power, Shiite rebels in Yemen found themselves increasingly under pressure Saturday as thousands protested against their rule and a group of nearby countries denounced their “coup.”

The leader of the Houthi rebels, Abdel-Malak al-Houthi, gave an impassioned speech defending dissolving Yemen’s parliament Friday as the only response to a power “vacuum” — one his group created by besieging the country’s president, who later resigned.

The ongoing unrest in the Arab world’s poorest country could benefit Yemen’s al-Qaida branch, considered by America as the world’s most dangerous wing of the terror group. And while the Houthis oppose al-Qaida, they also are hostile to the U.S. and critics say Shiite power Iran backs their territorial gains — something the rebels deny.

The six Arab countries of the Gulf Cooperation Council, led by Sunni-ruled Saudi Arabia and the United Arab Emirates, issued a statement Saturday carried by the official Saudi Press Agency calling for the U.N. Security Council to “put an end to this coup.”

“The Cooperation Council sees Houthi coup as an escalation that cannot be accepted under any circumstances,” the council said.

The council serves as a regional counterbalance to Iran, which the council previously has accused of meddling in their own countries’ internal affairs. Saudi Arabia, which long has provided an economic lifeline to Yemen, slashed aid following the Houthis’ insurrection and shows no sign of restoring it.

In a televised address, Shiite rebel leader Abdel-Malek al-Houthi repeatedly said his opponents wanted to advance “conspiracies” to cause chaos in a country in turmoil since the Houthis began their offensive in September. On Friday, the rebels dissolved parliament and formally announced they seized power in this country of 24 million people.

“The constitutional declaration … came to end the vacuum,” al-Houthi said. “It’s all in the interest of the people, and for the people, and for facing these threats and conspiracies against the people.”

In January, the rebels raided the presidential palace and besieged the residence of then-President Abed Rabbo Mansour Hadi. Within days Hadi and his Cabinet resigned. They remain under Houthi house arrest today.

Hadi was elected as a president in 2012 after a popular revolt toppled President Ali Abdullah Saleh, who is a Zaydi, a branch of Shiite Islam that exists almost solely in Yemen. Houthis, who are Zayidis, represent about 30 percent of Yemen’s population.

Saleh waged six-year-war against Houthis that ended in a cease-fire in 2010. It appeared that the old foes have joined forces during the Houthis’ advance from their northern Yemen stronghold. However Saturday, Saleh’s Congress Party issued a statement calling the Houthi declaration “an infringement on constitutional legitimacy” and called for renewed negotiations.

A statement from the leaders of three southern provinces also denounced the Houthi takeover as a coup and called Hadi the country’s legitimate president.

The Islah party, the Muslim Brotherhood’s branch in Yemen which opposes the Houthis, said they also rejected the rebels’ move and called for renewed talks.

The Houthis’ Revolutionary Committee is expected to form a new parliament and a five-member presidential council to succeed Hadi.

In its first decree Saturday, the committee appointed Mahmoud al-Subeihi as Yemen’s acting defense minister and Jalal al-Rowaishan as acting interior minister. The two held the positions in Hadi’s government and resigned with him last month.

An official close to al-Subeihi said the two ministers were being “forced” to return to their posts. He spoke on condition of anonymity because he wasn’t authorized to speak to journalists.

Political analyst Magid al-Muzhagi said the Houthi declaration had brought Yemen into an “unprecedented situation.” North and South Yemen only unified in 1990 and discussions about federal power sharing helped spark the Houthi rebellion.

“The repercussions will be severe on the fabric of Yemeni society especially with the lack of control on the ground,” he said.

On Saturday, thousands protested in Sanaa, as well as the cities of Hodeida, Ibb and Taiz. Meanwhile, thousands rallied in support of the Houthis at a sports stadium in Sanaa.

A bomb also exploded in a street leading to the capital’s presidential palace, wounding three people.