US President Donald Trump has lashed out at the mayor of San Juan and other officials in storm-ravaged Puerto Rico, contemptuous of their claims of a slow American response to the natural disaster that has threatened the island's future.

The mayor of the island's biggest city, San Juan, has said the response to the disaster is "not a good news story".

Rescuers are hard at work today after Hurricane Maria ravaged Puerto Rico, knocking out electricity to the entire island and triggering landslides and floods.

The US National Hurricane Centre said the "potentially catastrophic" storm is the most powerful seen in the Atlantic in more than a decade.

Puerto Rico's voters have overwhelmingly chosen for the territory to become the 51st US state in a non-binding referendum, the island's governor said.

Puerto Rico nationalist Oscar Lopez Rivera has been freed from house arrest after decades in custody.

Puerto Rico is closing 184 public schools in a bid to save money amid a deep economic crisis that has sparked an exodus to the US mainland in the past decade.

Federal authorities in Puerto Rico said they have seized more than 40,000 counterfeit condoms that allegedly came from China.