Trump backs off accusation that Obama founded IS

Donald Trump backtracked on his allegation that President Barack Obama and Hillary Clinton founded the Islamic State group.

Trump insists he was just being sarcastic - and as he often does - the Republican presidential nominee accused media of misconstruing what he said.

This time he blamed US broadcaster CNN although his comments on the militant group and the president were picked up across the news spectrum.

"Ratings challenged @CNN reports so seriously that I call President Obama (and Clinton) "the founder" of ISIS, & MVP. THEY DON'T GET SARCASM?," Trump wrote in a tweet.

— Donald J. Trump (@realDonaldTrump) August 12, 2016 " style="color:#fff;" class="twitter-post-link" target="_blank">Twitter Post Ratings challenged @CNN reports so seriously that I call President Obama (and Clinton) "the founder" of ISIS, & MVP. THEY DON'T GET SARCASM? — Donald J. Trump (@realDonaldTrump) August 12, 2016

Trump later attacked the media, and then said that IS gained in strength while Clinton was secretary of state.

— Donald J. Trump (@realDonaldTrump) August 12, 2016 " style="color:#fff;" class="twitter-post-link" target="_blank">Twitter Post ISIS gained tremendous strength during Hillary Clinton's term as Secretary of State. When will the dishonest media report the facts! — Donald J. Trump (@realDonaldTrump) August 12, 2016

Trump first made the accusation Wednesday at a rally in Florida, and repeated it in interviews the following day.

He appeared to be mimicking the argument that the US troop withdrawal from Iraq under Obama - with Clinton serving as secretary of state - created a vacuum that allowed the Islamic State group to emerge and flourish in Iraq and Syria.

He also said he considered Clinton - his Democratic rival for the presidency - to be the co-founder of the Islamic State group.

The Clinton team responded Thursday by calling the assertion outlandish.

"Anyone willing to sink so low, so often should never be allowed to serve as our commander-in-chief," Clinton wrote in a tweet.

But last month he also said that an appeal to Russian hackers to find deleted emails at the centre of a controversy dogging Clinton's campaign was also sarcastic.

Last week, Trump made the rare act of apoligising after he claimed to have seen secret Iranian footage of $400 million in cash being delivered to Tehran as payment for the release of US prisoners.

But that widely viewed footage is believed instead to show the moment in January when three of five American prisoners freed by Iran get off a plane in Geneva.