Tech leaders slam Donald Trump's presidency bid

US technology companies and start-up founders have joined forces with venture capitalists to denounce Republican nominee Donald Trump as a candidate for the president of the United States, arguing he would be a disaster for innovation.

A long list of tech luminaries including executives from Cisco, Apple, Instagram, Samsung, Snapchat Expedia, Slack, and Flickr, as well as former United States government chief technology officer Aneesh Chopra, penned an open letter campaigning against a Trump-led United States.

"We believe in an inclusive country that fosters opportunity, creativity and a level playing field. Donald Trump does not," they wrote.

"He campaigns on anger, bigotry, fear of new ideas and new people, and a fundamental belief that America is weak and in decline."

Trump's policies as president would run counter to the open exchange of ideas, free movement of people, and productive engagement with the outside world, the letter signatories argued.

The controversial ultra-conservative and populist Trump's immigration policies would also hurt the tech sector in the United States, the tech leaders argued, claiming around 40 per cent of Fortune 500 companies were founded by immigrants and their children.

Trump called for the public to boycott Apple after the IT giant fought a court order to help US law enforcement unlock an iPhone belonging to one of the terrorist shooters in last year's San Bernardino attack.

New UK PM fires salvo at tech tax dodgers

Tech companies are also facing a battle in the United Kingdom, where newly appointed prime minister Theresa May has promised to put the boot into tax-avoiding multinationals, singling out Amazon and Google.

"It doesn’t matter to me whether you're Amazon, Google or Starbucks, you have a duty to put something back, you have a debt to your fellow citizens, you have a responsibility to pay your taxes," May said in her first speech in the role.

The preceding government under David Cameron was sharply criticised for letting Google off with a sweetheart tax deal early this year, after reaching an agreement to pay just A$265 million in back taxes since 2005.

Google's turnover in Britain since 2005 has been in excess of £24 billion (A$42 billion).

Amazon has paid similarly low amounts in income tax in the region, giving the UK taxman just £12 million (A$22 million) for the 2014-15 year, despite raking in £5.3 billion in sales (A$9.3 billion).