The director of CBI Scotland has questioned the conduct of the Holyrood inquiry into Donald Trump's plans for a golf resort in Aberdeenshire.
Mr McMillan questioned the motives of the committee
Iain McMillan told BBC Scotland it risked sending a message to the world that the country had a "troublesome" attitude to business.
The head of the committee holding the probe denied it was a "fishing trip".
Meanwhile the Trump Organisation has now agreed to appear before the inquiry, despite earlier refusing.
Mr McMillan said an investigation would be justified if there was evidence or informed suspicion of wrongdoing, but that so far neither had been turned up.
He asked why the inquiry, by the parliament's by the local government committee, went ahead despite Scotland's top civil servant, Sir John Elvidge, judging that nothing improper had taken place.
And he warned that if the inquiry continued simply as a "fishing expedition", it would send a strong message to the world that Scotland was not open for business.
"Act on evidence, act on reasonable suspicion - but where there is none, close the investigation down and let this development application run its course," he said.
"That's what's best for Scotland - let's do what's best for Scotland and, for heaven's sake, stop being our own worst enemy."
The committee inquiry was launched after the Scottish Government called in the planning application to build a £1bn golf resort, featuring two courses, a hotel and housing, on the Menie Estate.
Donald Trump's team has now agreed to attend the hearing
The application was narrowly rejected by Aberdeenshire Council's infrastructure services committee in November.
Labour MSP Duncan McNeil, convener of the local government committee, said it was right to investigate the affair.
"All parties on the committee are acting on behalf of the parliament to scrutinise the actions of government - to examine the process, not the merits, of the planning application," he told BBC Radio Scotland's Good Morning Scotland.
He insisted: "It is not a fishing trip."
The committee has already questioned First Minister Alex Salmond twice on the government's involvement in the affair and taken evidence from the government's chief planner, Jim Mackinnon, and Alan Campbell, the chief executive of Aberdeenshire Council.
Despite their earlier refusal, Representatives of the Trump Organisation said they would be honoured to appear before MSPs, but pointed out they thought it was unnecessary.