Republican presidential nominee Donald Trump has said that President Barack Obama is "the founder" of the Islamic State (IS) terror group.

During a campaign rally in Sunrise, Florida, Trump on Wednesday criticised Obama's counter-terrorism strategy and said he was "the founder of IS" and that his rival in the presidential race, Hillary Clinton, is the "co-founder" of this terrorist group, EFE news reported.

"IS is honouring President Obama. He is the founder of IS. And I would say the co-founder is crooked Hillary Clinton," said Trump while rally-goers cheered 'Lock her up!' directed at Clinton.

Trump criticised that Obama has refused using the term "radical Islamic terrorism" to refer to the attacks in Orlando, Florida and San Bernardino, California.

Trump also took aim at Clinton for her refusal to use that term as well: "She doesn't want to say it, 'cause she doesn't want to offend the president, because then bad things could happen to her if she offends the President."