Passengers flying out of Glasgow Airport have experienced security delays due to a strike by staff.
Members of the Unite union at Glasgow and Aberdeen Airports walked out from 04.00 until 16:00 - the first of two 12-hour strikes by security staff, fire and operations teams.
It follows a breakdown in talks about pensions and pay with owner AGS Airports.
Glasgow Airport said queues at security were "longer than normal".
It tweeted: "We apologise to our customers for the delay at security this morning.
"Following the commencement of industrial action and transition to our contingency in security, we have experienced longer than normal queues."
We apologise to our customers for the delay at security this morning. Following the commencement of industrial action and transition to our contingency in security, we have experienced longer than normal queues. We thank you for your patience and understanding.— Glasgow Airport (@GLA_Airport) June 7, 2019
The strike did not involve check-in staff and baggage handlers.
However, after the strike ended at 16:00 it emerged that there were flight delays as contingency staff handed over to regular workers.
Some flights were delayed for an hour.
On social media - the airport explained that operations were temporarily suspended.
Unite spokesman Pat McIlvogue confirmed there would be further strike action - blaming airport bosses for "continuing to ignore" union bids to resolve the dispute.
He said: "The industrial action has severely disrupted Glasgow Airport's operations, despite the underhand tactics by management which included substituting fire safety officers with other staff on site who were questionably trained for the job.
"It's a shame that passengers' travel has been disrupted but this is 100% the fault of Glasgow Airport management."
A further 12-hour strike is planned at both airports on 10 June. At Glasgow, this will be followed by a four-hour walkout on 14 June and a strike from 08:00 to 16:30 on 21 June.
Aberdeen Airport said there was no disruption to passengers.
Steve Szalay, managing director, said: "This is not a situation that we want to be in but it's been business as usual here.
"We'll have 10,000 people travelling today and they've been coming in and out without disruption."
AGS had earlier said "robust contingency plans" would be put in place to ensure "business as usual" at both airports.
About 400 people are thought to have joined the strike in Glasgow alone, but airport bosses brought in the same number of staff to cover.
Unite the union
About 300 people were expected to be on strike at Aberdeen.
AGS Airports Limited owns Glasgow, Aberdeen and Southampton airports.
The union claims the company closed the consultation process on pensions on 24 May, as it attempted to close a defined benefit pension scheme.
This, they say, broke an Acas agreement made in 2016 to keep the scheme open to existing members.
An AGS spokesman said: "We have been in talks since January and, despite attending Acas, there continues to be no willingness whatsoever on the part of Unite to engage in any constructive dialogue.
"We made a significant improvement on our initial pay offer, which was increased from 1.8% to 3% in line with demands.
"This was rejected by Unite without any further consultation with members, and the union continues to deny them the right to make a decision on the offer of 3%."
He added: "In regards to our final salary pension scheme, it is simply unaffordable with the cost to the company due to rise to 24.7% per employee.
"We tabled a generous compensation package for the remaining members, which again was rejected by Unite without first consulting its members.
"As always, we remain open to continuing dialogue with Unite to resolve this dispute."