US President Trump has not abandoned his old, unsecured Android smartphone

US President Donald Trump has not abandoned his old Android smartphone and is still using the "unsecured" device to post his tweets, raising security concerns among the intelligence community.

Trump, who was thought to have relinquished his old Android phone for a new, secure device provided by the government, has been using his old, unsecured Android phone to post on Twitter since moving to Washington late last week, according to a report in 'The New York Times'.

"The president's use of an unsecured personal device raises concerns that his desire to use his old smartphone could be exposing him and the nation to security threats," the report said yesterday.

Trump is using the Android smartphone mainly to post on Twitter and not to make calls, it said, adding that was unclear what security measures had been put in place on the device and how vulnerable he could be to someone stealing data or breaking into his Twitter account.

"The absolutely minimum Trump could do to protect our nation is to use a secure device to protect him from foreign spies and other threats," the report quoted Senator Ron Wyden, a Democrat from Oregon on the Intelligence Committee, as saying.

"It would be irresponsible in the extreme for the commander in chief to use an unsecure device that could be easily hacked or intercepted," Wyden said.

Trump's use of the personal device is particularly notable given his criticism of Hillary Clinton for using a personal email address and server when she was secretary of state, it said.

"As president, he is the biggest sitting target in the world," said Kevin Bankston, the director of New America's Open Technology Institute.

In 2009, Barack Obama had fought to become the first US President with a smartphone, though he won, the use of a White House-issued secure device came with many rules.