Republican frontrunner Donald Trump has accused U.S. President Barack Obama of establishing the Islamic State (IS) group that is wreaking havoc from West Asia to European cities.

A moment later on another topic, he referred to the President by his full legal name: Barack Hussein Obama. “In many respects, you know, they honour President Obama,” Mr. Trump said during a raucous campaign rally outside Fort Lauderdale, Florida. “He is the founder of ISIS.” He repeated the allegation three more times for emphasis.

The Republican presidential nominee in the past has accused his opponent, Democrat Hillary Clinton, of founding the militant group. As he shifted the blame to Mr. Obama on Wednesday, he said that “crooked Hillary Clinton” was actually the group’s co-founder.

Mr. Trump has long blamed Mr. Obama and his former Secretary of State for pursuing West Asian policies that created a power vacuum in Iraq that was exploited by the IS. He’s sharply criticised Mr. Obama for announcing he would pull U.S. troops out of Iraq, a decision that many Obama critics say created the kind of instability in which extremist groups like the IS thrive.

The White House declined to comment on Mr. Trump’s accusation.

The IS group began as Iraq’s local affiliate of the al-Qaeda, the group that attacked the U.S. on 9/11. The group carried out massive attacks against Iraq’s Shia Muslim majority, fuelling tensions with the al-Qaeda’s central leadership.

The local group’s then-leader, Jordanian-born Abu Musab al-Zarqawi, was killed in 2006 in a U.S. airstrike but is still seen as the IS’ founder.

Mr. Trump’s accusation and his use of the President’s middle name, Hussein echoed of previous instances where he’s questioned Mr. Obama’s loyalties.

In June, when a shooter who claimed allegiance to the IS killed 49 people in an Orlando, Florida nightclub, Mr. Trump seemed to suggest Obama was sympathetic to the group when he said Obama “doesn’t get it or, or he gets it better than anybody understands.”

In the past, Mr. Trump has also falsely suggested Mr. Obama is a Muslim or was born in Kenya, where the President’s father was from.

The President, a Christian, was born in Hawaii. Mr. Trump lobbed the allegation midway through his rally at a sports arena, where riled-up supporters shouted obscenities about Ms. Clinton and joined in unison to shout “lock her up.” He railed against the fact that the Orlando shooter’s father, Seddique Mateen, was spotted in the crowd behind Ms. Clinton during a Monday rally in Florida, adding, “Of course, he likes Hillary Clinton.”

Sitting behind Mr. Trump at his rally on Wednesday was former Republican Mark Foley, Republican from Florida, who resigned in 2006 after allegations he sent sexually suggestive messages to former House pages.