Edinburgh Airport was evacuated and closed after a "potentially suspicious bag" was identified in the search area at 1.50pm.
Gordon Dewar, chief executive of the airport, told Sky News that police found there was no threat and efforts were now being made to return the airport to normal.
Flights were cancelled and inbound aircraft diverted after the alert.
Mr Dewar told Sky News: "Round about two o'clock we had an unidentified threat that triggered an investigation in terms of being an issue of airport security.
"Unfortunately that meant as part of that we had to evacuate the terminal building so it's effectively been closed since about 2.15pm and we've not been able to operate as normal, clearly in that time there has been a very extensive investigation with police and authorities and I'm delighted to say that they've now concluded that there is no threat, obviously it has taken some time to do that, so the challenge now will be once they have handed back the site to us that we get the airport back up to full operation.
"We'll do that relatively quickly but inevitably passengers and aircraft may not be where we need them and it will be a number of hours yet before we can get to some normality.
"We now this causes huge disruption and upset to people, we have done our best to mitigate that and make people as comfortable as possible in the circumstances but it's a cold wet day in Edinburgh, there's limited facilities when the terminal is shut and we just want to make sure people can now get away on their travels as best as possible.
"All we can do now is keep people informed, try to help the airlines get back to normality and get as many people away on their journey as possible."
Bomb disposal experts had been called to the scene to investigate the suspect bag.
Police Scotland said the airport would now "begin to reopen with cordons and road restrictions lifted imminently".
Chief Inspector David Campbell said: "As part of a routine bag search at the airport, suspicions were raised about the contents of one item of hand luggage and the decision was taken to evacuate the airport while the appropriate inquiries could be carried out.
"We are now satisfied there isn't, nor was there ever, any risk to the public and the airport will now begin to reopen.
"We would like to thank the public for their patience and co-operation during the emergency service response."