Hillary Clinton's use of a private email server to conduct government business when she was US secretary of state was a mistake, but did not endanger national security, President Barack Obama has said.

In an interview on CBS's 60 Minutes TV programme, Mr Obama said public officials had to be more sensitive about how they handled information and personal data.

But he also said the criticism of Mrs Clinton, who is leading the Democratic race for the presidential nomination, had been "ginned up" because of politics.

"I think she'd be the first to acknowledge that maybe she could have handled the original decision better and the disclosures more quickly," Mr Obama said.

The president downplayed the threat to national security and when it was pointed out that his administration has prosecuted people for having classified material on their private computers, said he did not get the impression there was an intent to "hide something or to squirrel away information".

He also said he was not initially aware of her use of the private email server. Questions are still being raised about the security of that system.

Mr Obama also discussed his views on Syria during the interview. The administration is abandoning a failed Pentagon effort to build a new ground force of moderate rebels and overhauling its approach to instead partner with established rebel groups.

The change also reflects growing concern in Mr Obama's administration that Russia's intervention has complicated the Syrian battlefield and given new life to President Bashar Assad.

Mr Obama said he was "sceptical from the get-go" about the notion of creating an army of moderate forces within Syria.

"My goal has been to try to test the proposition, can we be able to train and equip a moderate opposition that's willing to fight Isil (another name for the Islamic State, or IS militants)? And what we've learned is that as long as Assad remains in power, it is very difficult to get those folks to focus their attention on Isil," he said.

Mr Obama said part of the strategy behind the administration's efforts was to "try different things", adding that "in a situation that is as volatile and with as many players as there are inside of Syria, there aren't any silver bullets".

While the Pentagon is abandoning its effort to train rebels, a CIA programme that since 2013 has trained some 10,000 rebels to fight Assad's forces is continuing.