Hillary Clinton's assertion that she used a personal email account for government business because she wanted to carry a single device clashes with documents obtained by the Associated Press, which show the then-secretary of State used both an iPhone and a Blackberry for work, the news service reported.

Four emails between Clinton and top advisers that the AP obtained as part of a 2013 Freedom of Information Act request also show that the presumed Democratic frontrunner in the 2016 White House race mixed private and official conversations. The messages were sent to and from her private email address, hosted on her New York property, as opposed to a government-run email account, the agency said.

In reply to a message adviser Huma Abedin sent the secretary in September 2011, Clinton – apparently by mistake – posed questions that appear to be about decorations.

"I like the idea of these," she wrote. "How high are they? What would the bench be made of? And I'd prefer two shelves or attractive boxes/baskets/ conmtainers [sic] on one. What do you think?"

Abedin, whose original message contained an AP story about a drone strike in Pakistan, asked for clarification. "Did u mean to send to me?" she wondered.

"No -- sorry!" Clinton replied. "Also, pls let me know if you got a reply from my ipad. I'm not sure replies go thru."

Clinton spokesman Nick Merrill said on Tuesday that the then-secretary used her iPad from time to time, primarily to read news clippings.

A few weeks ago, Clinton responded to criticism about her communication habits by arguing that using a single Blackberry was a matter of convenience, the Washington Post recalled.

"Looking back, it would have been better for me to use two separate phones and two email accounts," she said in early March at a New York news conference. "I thought using one device would be simpler, and obviously, it hasn't worked out that way," she added.

But the new revelations "(undercut) Clinton's argument for having a private, nongovernmental e-mail server," the newspaper added.