Teresopolis, Jan 16 (Agencies): Brazil declared three days of national mourning for nearly 560 people killed near Rio de Janeiro this week in the country's worst flood disaster on record.

Emergency workers in the disaster zone, in the Serrana region just north of Rio, were overwhelmed by the body count. Refrigerator trucks had to be brought in to store corpses.

Workers transporting bodies said they feared the overall death toll could more than double as rescuers reached outlying hamlets.

President Dilma Rousseff declared the three days of mourning, Government news agency Agencia Brasil reported. Rio de Janeiro State authorities said their State will observe a full week of mourning starting on Monday.

"I think in the end we'll see more than 1,000 bodies," said a funeral worker in Teresopolis, Mauricio Berlim. "In one village near here, Campo Grande, there were 2,500 homes and not one is left standing," Berlim said.

Authorities also made an urgent appeal for donations of blood, bottled water, food and medicine.

At least four refrigerated trucks were parked out the front of an overflowing makeshift morgue inside a church in Teresopolis.

Body-recovery efforts have been hampered by tons of mud that, in some cases, have cut villages off and made them accessible only by helicopter—but flights were limited by persistent rain that limited visibility in the rough terrain to just a couple of hundred meters.

At least a dozen remote hamlets remain out of touch, and one witness reported seeing a group of people buried in their car by a river of mud.

Some 14,000 people have been forced to flee their homes, Civil Defense officials said.

The disaster, which media called the worst tragedy of its kind in Brazil's history, struck Wednesday before dawn, as families were sleeping.

Seasonally heavy rains were suddenly intensified by a cold front, dumping a month's worth of precipitation in just eight hours.