Hurricane Matthew has been downgraded to a Category 1 storm as it sweeps along the east coast of the US towards North Carolina.

Northern Florida, Georgia and South Carolina remain on high alert with hundreds of miles of coastline still in danger from torrential rain and storm surge.

The storm has toppled trees and knocked out power to more than half a million people in the Caribbean, but southern Florida has avoided severe damage, despite a number of people reportedly losing their lives.

The Florida death toll is still unclear with reports ranging between 4 and 6 casualties.

"We have been very fortunate that Matthew's strongest winds have remained a short distance offshore of the Florida and Georgia coasts thus far, but this should not be a reason to let down our guard," the Hurricane Centre said.

Matthew is now moving toward the northeast at 12 mph with the eye of the storm just off South Carolina's coastline.

The storm has already claimed the lives of at least 887 people in Haiti, and is expected to hit North Carolina later, with state governor Nikki Haley saying earlier "now is the time we ask for prayer." 

Speaking at the White House, President Obama stressed the threat to the Jacksonville area, and emphasised "this is still a really dangerous hurricane."

In a media briefing he warned: "We can always replace property. We cannot replace lives."

With outbreaks of cholera claiming more lives in Haiti in the aftermath of the storm, Christian Aid said the situation is set to remain critical for the next 18 months.

Prospery Raymond from the charity said: "The south part of Haiti is really affected by Hurricane Matthew. 

"The population are really in need of water, shelter, materials ... Compared to the earthquake this emergency is very, very critical."

Minister for Foreign Affairs, Charlie Flanagan said yesterday Ireland will provide humanitarian assistance to the region once “once a clearer picture of humanitarian needs has emerged.”

“The damage and destruction caused by Hurricane Matthew in Haiti in recent days is another devastating blow to communities previously affected by the earthquake in 2010,” he said.

“The death toll continues to rise and we know that many thousands of people have lost their homes and possessions in the aftermath of the strongest storm to hit the region in a decade.”