US authorities have approved Alphabet Inc's application to use its experimental Project Loon balloons to provide emergency mobile phone service to disaster-stricken Puerto Rico, as Tesla said it would send more battery supplies.

In the aftermath of Hurricane Maria, Puerto Rico has struggled to regain communications services.

The US Federal Communications Commission (FCC) said 83 per cent of mobile sites remain out of service, while wireless communications companies had deployed temporary sites.

Google parent company Alphabet, which announced its Project Loon in 2013 to use solar-powered, high-altitude balloons to provide internet service in remote regions, said in an FCC filing it was working to "support licensed mobile carriers' restoration of limited communications capability" in Puerto Rico.

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Earlier, FCC Chairman Ajit Pai announced he was forming a Hurricane Recovery Task Force with an emphasis on addressing challenges facing Puerto Rico and the US Virgin Islands.

"It is critical that we adopt a coordinated and comprehensive approach to support the rebuilding of communications infrastructure and restoration of communications services," Mr Pai said in statement.

Separately, Puerto Rico Governor Ricardo Rossello said on Twitter that he had a "great initial conversation" with Elon Musk, the chief executive of Tesla Inc.

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Mr Musk said the company would send more battery installers to Puerto Rico to help restore power after Hurricane Maria knocked out all power on the island over two weeks ago.

Mr Musk said he was diverting resources from a semi-truck project to fix Model 3 bottlenecks and "increase battery production for Puerto Rico & other affected areas."

In late September, Tesla said it was sending hundreds of batteries that can store power generated by solar panels to Puerto Rico to provide emergency help in the wake of Hurricane Maria.

Tesla is currently working on "the world's biggest" lithium ion battery to help with power supply in South Australia.

What is Project Loon?

Project Loon sends balloons intro the stratosphere — twice as high as commercial airliners — where they are self-powered by solar panels.

Project Loon balloons will float in the stratosphere and be powered by solar panels. ( Supplied: Project Loon )

The project works by ground stations connecting to the local internet infrastructure and beaming signals to the balloons.

Users below attach an antennae to their house, which can communicate with the 'mesh network' of balloons above.

The company had previously conducted connectivity tests in Australia, New Zealand and several South American countries.

In 2016, a test site was set up in Puerto Rico to launch what the project called "a handful of test balloons".

The balloons were used in March to bring connectivity to Peru after the country was hit by extreme rains and flooding.

By June this year, Loon balloons had travelled a combined distance of 19 million kilometres.

Project Loon's launch base in Puerto Rico during 2016. ( Supplied: Project Loon, file )

ABC/Reuters