DUP mole 'wore a wire' to leak meeting to Jamie Bryson
The "senior" DUP executive member behind leaking the speech made by party leader Sir Jeffrey Donaldson was wearing a wire, the BBC understands.
The member used the recording device to relay the speech live to loyalist activist Jamie Bryson.
Mr Bryson then posted what Sir Jeffrey Donaldson said on X, formerly Twitter.
It is understood the party leadership believed the speech was being leaked via a mobile phone and called for all phones to be switched off.
But the live feed continued to be posted on X.
Mr Bryson refused to disclose who leaked the speech, but told the BBC's Good Morning Ulster programme he was helped by senior party members.
"Senior people in the DUP felt so exercised about this and felt that this was such a defining moment, that they took the step that they did," Mr Bryson said.
"Obviously I wasn't in the room, the venue clearly wasn't bugged by some hidden device so there was clearly senior people - plural - within the DUP who felt so strongly about this that they took this extraordinary, unprecedented step."
Immediately after the five-hour private meeting on Monday night, Sir Jeffrey said he was disappointed that a member of the DUP executive had "betrayed" the party.
He also disputed some of what was posted on Mr Bryson's X account, insisting it was inaccurate.
On Tuesday morning, the DUP leader said there would be an investigation into how parts of the meeting were leaked.