In a televised statement, the group said a five-member council would act as the president for an interim period.

The group took control of the capital Sanaa in September, forcing the resignation of President Abed Rabbo Mansour Hadi in January.

The announcement comes after the failure of UN-brokered peace talks.

The Houthis set a Wednesday deadline for political parties to reach an agreement on ending the country's political turmoil, threatening to act unilaterally otherwise.

The rebels move would mark "a new era that will take Yemen to safe shores'', the statement said, according to Associated Press.

Analysis: Sebastian Usher, BBC World Service

The declaration will be seen by many Yemenis as the final stage of a Houthi coup, although some may feel that it could offer some hope of greater stability.

Government decisions will now in effect be dictated by a revolutionary committee, dominated by the rebels.

The Houthis delivered their message from the Republican palace in Sanaa to a huge gathering of political, military and tribal figures in an effort to show the range of their support.

Their writ will not be recognised by many Sunni and southern leaders, threatening Yemen with a further descent into chaos.

The UN's point man on Yemen, Jamal Benomar, headed straight to Saudi Arabia after the failure of talks to try to achieve some kind of political consensus there.

It is a sign of how concerned the Saudis are over what they see as an Iranian-backed Shia takeover in a country where they're accustomed to calling the shots.

Who are the Houthis?

The situation in Yemen escalated last month when the Houthis seized a key aide of President Hadi, in an attempt to block a draft constitution.

They later took the presidential palace and other key buildings, prompting Mr Hadi's resignation. He said he could not continue in his post under such pressure

He and and other ministers have been under house arrest since then.

Iran has been accused of giving financial and military support to the Houthis - something both have denied.

Yemen has been riven by instability since protesters inspired by the Arab Spring forced the overthrow of President Ali Abdullah Saleh in 2011, who is believed to have been backing the Houthis.

The country is also fighting an al-Qaeda insurgency with the help of US drones.

BBC