WASHINGTON (Reuters) - The troubled mobile phone maker BlackBerry still has at least one very loyal customer: U.S. President Barack Obama.

At a meeting with youth on Wednesday to promote his landmark healthcare law, Obama said he is not allowed to have Apple's smart phone, the iPhone, for "security reasons," though he still uses Apple's tablet computer, the iPad.

Apple was one of several tech companies that may have allowed the National Security Agency (NSA) direct access to servers containing customer data, according to revelations by former NSA contractor Edward Snowden. The companies deny the allegation.

Obama fought to keep his BlackBerry after coming to the White House in 2009, though he said only 10 people have his personal email address. Neither George W. Bush nor Bill Clinton used email during their presidencies.

BlackBerry, a Canadian company formerly known as Research In Motion Ltd, virtually invented the idea of on-the-go email, but lost its market stranglehold as rivals brought out more consumer-friendly devices, like Apple's iPhone and phones using Google's Android software.

The company recently halted plans to be sold and is trying to chart a new course by focusing on large business and government clients.

(Reporting by Anna Yukhananov; Editing by Paul Simao)