( L - R ) Obama, Préval

CHICAGO (CMC):

United States Democratic presidential candidate Barack Obama has called for more aid for Haiti, which has been battered by successive storms that have killed more than 600 people over the past few weeks.

"My thoughts and prayers are with the hundreds of thousands of Haitians struggling to survive the floods and devastation caused by the hurricanes

And tropical storms

of the past six weeks, and I extend my deepest sympathies to those affected by the loss of more than 500 lives," Obama said.

"Time is of the essence in helping Haiti cope with this humanitarian crisis and begin to recover. Tens of thousands of Haitians have been displaced and left without shelter," Obama said, noting that that Haiti's already-struggling agricultural sector had also been devastated.

Haitian Government officials said about one million people had been left homeless following the passage of four storms on recent weeks.