Yemen's President Abd-Rabbu Mansour Hadi has declared as invalid and unconstitutional all actions taken by the Shia Houthis after September 21 when the group moved into Sanaa.

In a statement issued to Al Jazeera late on Saturday, Hadi said that he was upholding decisions adopted by the national dialogue and the agreement reached by Gulf Arab states for a political solution in the Arabian Peninsula nation.

He called on the international community to protect the political process.

The statement was signed by Hadi "as president of the republic".

An aide to Hadi told AFP news agency that he will call on parliament to meet in Aden, as powerful tribes in the southern provinces of Marib, Jawaf and Baida urged him to declare Sanaa an "occupied city".

The aide said Hadi "remains the legitimate president and that he resigned under pressure from Houthis".

Earlier on Saturday, Hadi managed to slip house arrest in Sanaa, the capital, and is now in his home town of Aden.

Hadi arrived in his power base in the south on Saturday afternoon, after he left his home in Sanaa, which was under siege from the Houthis, Al Jazeera's Mohamed Vall, reporting from Aden, said.

Following his return, Hadi held a meeting with the security council of Aden province to discuss the situation in the country.

Our correspondent also said that security forces were on alert in Aden, where Hadi has strong loyalty among Sunni Muslims.

Talks between the country's warring factions were immediately suspended after Hadi escaped house arrest, sources told Al Jazeera.

Al Jazeera has learned that Jamal Benomar, the UN special envoy to Yemen, held an emergency meeting with Houthi leaders in Sanaa to discuss possible withdrawal of their fighters from the city to normalise the political situation.

The news came as Houthi fighters opened fire on protesters in the central Yemeni city of Ibb on Saturday, killing one person and wounding another, activists said.

Clashes in Ibb

The crowd had gathered in a public square in Ibb after a new power-sharing deal was reached on Friday to demonstrate against the Houthis' role in the overthrow of Hadi's government last month.

Following the shooting, thousands more people took to the streets in protest. Witnesses said the Houthis were deploying more security forces in response.

Yemen's feuding political parties agreed on Friday to create a transitional council to help govern the country and allow a government to continue operating with input from rival factions after the effective Houthi takeover.

Western countries are worried that unrest in Yemen could create opportunities for al-Qaeda in the Arabian Peninsula (AQAP) to plot more attacks against international targets.

Late on Friday, a drone destroyed a car carrying suspected members of AQAP in Shabwa province, a bastion of the armed group in the rugged mountains of southern Yemen, killing at least three people, residents said.

The US has acknowledged it carries out drone strikes against targets in Yemen but does not comment on specific attacks.

The strikes, which have sometimes killed civilians, have angered many people in the country.

Hadi was seen as a supporter of the use of drone strikes against AQAP.