QUITO (REUTERS) - A powerful earthquake measuring magnitude-6.0 struck Ecuador on Thursday (April 21), as the country was still struggling to recover from a deadly quake that killed 587 people, the United States Geological Survey (USGS) said.

The latest quake hit about 100km north-north-west of Portoviejo and at a depth of 10km, said the USGS. There were no immediate reports of damage and there was no tsunami warning.

President Rafael Correa said on Twitter that three aftershocks were registered on Thursday night, adding "have strength!".

Last Saturday's deadly quake was a massive 7.8-magnitude.

"We're trying to survive. We need food," said Mr Galo Garcia, a 65-year-old lawyer as he waited in line for water from a truck in beachside village of San Jacinto. "There's nothing in the shops. We're eating the vegetables we grow."

A crowd nearby chanted, "We want food."

Mr Correa's socialist government, facing a mammoth rebuilding task at a time of greatly reduced oil revenues in the Opec nation, said there was no lack of supplies, just problems with distribution that should be quickly resolved.

The government quickly moved supplies to the main towns and set up shelters for more than 25,000 people in soccer stadiums and airports, but shattered roads have impeded the operation.

On streets near Pedernales, one of the worst-hit towns, children from rural areas held signs begging for food. Many people left villages to seek help, and those who stayed behind felt the pinch.

"All of us here have been marginalized. The others are receiving things, but we're not," said Mr Darwin Gachila, 33, as he cradled his baby daughter, flanked by his wife and two other children in the small village of Cojimies.

A government official at a food storage point outside the town of Pedernales asked a supplicant, Mr Jose Gregorio Basulor, 55, to stay calm. "I can be patient but not the children!" he shouted back. "They are crying."

Interior Minister Jose Serrano, speaking from an aid convoy nearby, stressed that the government was focusing on house-by-house distribution to ensure no one was overlooked.

Mr Correa has said Ecuador would temporarily increase some taxes, offer assets for sale and possibly issue bonds abroad to fund reconstruction after Saturday's 7.8-magnitude quake. He has estimated damage at US$2 billion to US$3 billion.

"Hopefully they won't increase the country risk because of the quake we suffered and hopefully we can issue these bonds soon," Mr Correa said on Thursday night. A raft of temporary tax increases should raise between US$650 million and US$1 billion, the government said on Thursday, stressing that those in areas hit by the quake would be exempt.

The 487 megawatt hydroelectric dam Sopladora, which is still in an experimental phase, could be one of the assets put on sale, Mr Correa said.

Lower oil revenue had already left the country of 16 million people facing near-zero growth and lower investment.

Ecuador's worst earthquake in nearly seven decades also injured 8,340 people, left 155 missing and damaged close to 2,000 buildings, according to the government.

Scores of foreign aid workers and experts have arrived and 14,000 security personnel were keeping order, with only sporadic looting.

"There are rumors there's a shortage of water," Mr Correa said late on Wednesday, responding to complaints about the aid operation. "We have plenty of water. The problem is distribution," he said.

Mr Correa said the death toll would have been lower had Ecuadoreans respected stricter building regulations that were introduced after the 2010 earthquake in Haiti that killed more than 300,000 people.

Ecuadoreans had a mixed reaction to tax increases and another measure to donate one day's salary to help relief work.

"Nobody likes paying taxes because even before the earthquake things were difficult," said student Isaac Andrade, 27, in the city of Guayaquil. "But I think it's consistent with the spirit of solidarity."

The government appealed for tourists to keep coming to fuel an industry that generated US$1.7 billion last year. But visitors may be put off by health warnings from the quake zone.

One charity, CARE International, said there was an immediate threat of mosquito-borne diseases including the Zika virus and dengue fever.

"There is a lot of stagnant water which greatly increases the number of breeding sites for mosquitoes," said Ms Lucy Harman, emergency team leader in Ecuador for CARE, which was supplying water purification tablets and temporary water tanks.

Rescuers were using face masks against the smell of decomposing bodies, while soldiers were vaccinated before being deployed into quake-hit areas.

The United Nations and partners were to launch an appeal on Friday to help an estimated 350,000 people in need of aid.