US President Donald Trump has blamed Puerto Ricans for failing to do enough to dig out from damage caused by Hurricane Maria, saying criticism levelled at his government for the slow response was driven by politics.
Ten days after the devastating storm wiped out power and communications systems, more than half of the 3.4 million people who live on the island do not have access to drinking water, and 95 per cent remain without power, the Pentagon said.
Trump, who was spending the weekend at his private golf club in New Jersey, fired off a series of angry tweets early on Saturday complaining that media coverage of the suffering was unfair, and took aim at the mayor of San Juan, the island's largest city.
On Friday, Carmen Yulin Cruz criticised Trump's Republican administration and begged for more help, pleas that received widespread television coverage in mainland US.
"Such poor leadership by the Mayor of San Juan and others in Puerto Rico who are not able to get their workers to help," said Trump, who is slated to visit the island on Tuesday. "They want everything to be done for them when it should be a community effort."
Maria has destroyed roads, making it difficult to get food, water and fuel around the island. The hurricane has killed at least 16 people.
Cruz, who has been living in a shelter after her home was destroyed in the hurricane, said municipal employees were working as hard as they could. She also said her complaints had resulted in more food and water being provided.
"Actually, I was asking for help - I wasn't saying anything nasty about the president," Cruz said on MSNBC. "I am not going to be distracted by small comments, by politics, by petty issues."
Trump's comments drew swift condemnation on the mainland.
"The tweets this morning are despicable, are deplorable, are not statesman-like at all," said New York City Council Speaker Melissa Mark-Viverito, a Democrat born in Puerto Rico.
"He needs to be in charge, he needs to take control, he needs to demonstrate some level of empathy over what is happening," Mark-Viverito said on CNN.
Trump was scheduled to speak by telephone to the governor of Puerto Rico, Ricardo Rossello, and other officials from the region on Saturday.
The Trump administration has given Puerto Rico's government "whatever we ask for" in the immediate aftermath of the hurricane, Rossello has said. But he warned that the US Congress would need to help rebuild the island.
"If congress doesn't take action with a significant package, then we are looking at a possible humanitarian crisis," he said. "What are the effects of falling into that predicament? Massive exodus without a doubt."
Police officers, firefighters and National Guardsmen loaned by other states were beginning to arrive to help local officials, Rossello said.
The US business community was rallying to donate cash, with more than $US24 million ($A31 million) donated to relief charities as of Friday, said Marc DeCourcey of the US Chamber of Commerce Foundation.
San Juan resident Judith Berkan said power shortages and long lines for cash, food, petrol, and medical clinics were wearing people down.
"Although there are great moments of solidarity on the ground here, you can also see that patience is growing thin."
