Washington, Oct 7 (IANS): The death toll from Hurricane Matthew, which barrelled towards the southeastern United States, in Haiti has climbed to 264, authorities said, forcing the US President Barack Obama to declare a state of emergency.

Emergency officials in Haiti's Sud province, which bore the brunt of the storm's impact, provided the new fatality figure just hours after Interior Minister Francois Anick Joseph cited a provisional death toll of 108.

Matthew, the most powerful hurricane to strike the Caribbean since 2007, made landfall in southwestern Haiti on Tuesday as a Category 4 storm with maximum sustained winds of 230 kph.

A partial evaluation indicates that more than 20,000 homes were severely damaged, Joseph said, describing the storm's impact as a "catastrophe."

The search for additional casualties continues, authorities said.

Most of the victims were killed by falling trees, flying debris and swollen rivers.

Due to the emergency declaration in Florida, the Department of Homeland Security and Federal Emergency Management Agency are authorised to coordinate all disaster relief efforts, Xinhua news agency reported.

Meanwhile, local authorities issued a mandatory evacuation order on Thursday for nearly 1.5 million coastal residents in preparation for the hurricane, one of the most powerful storms to hit the region in a decade.

"This storm will kill you. We don't have much time left," said Florida Governor Rick Scott at a press conference.

According to the US National Hurricane Centre in Miami, Florida, Hurricane Matthew remained a Category 3 hurricane as of Thursday morning.

There was still possibility that it would evolve into a Category 4 storm in approaching the east coast of Florida, said the Centre.

Matthew is now moving on to the coast of the US. The US National Weather Service warned on Thursday that the hurricane could be the worst storm seen in Florida for decades. Over 2 million people have been ordered to evacuate coastal areas.