LONDON (AP) — Border guards at British airports will walk off the job July 26, the day before the London Olympics begin, creating an Olympic-sized logistical headache for British officials.

Members of the Public and Commercial Services Union voted for the 24-hour strike in a dispute over pay and job losses.

Even without the strike, London’s Heathrow Airport has been beset for months by sporadic long lines at passport control, which the union blames on government spending cuts. The problem had eased in the last week as thousands of Olympic VIPs arrived for the games, but a walkout threatens a return of the endless waits at the worst possible moment for Britain’s international image.

Home Secretary Theresa May, Britain’s interior minister, called the decision to stage a strike on the eve of the games “shameful.” She said the government would “put contingency arrangements in place to ensure we can deal with people coming through the border as smoothly as possible.”

Jeremy Hunt, the top government official handling the Olympics, said he was “absolutely confident” that the government would be able to minimize any disruption.

During previous border guard strikes in November and May, the government drafted in managers and civil servants — including Prime Minister David Cameron’s press secretary — to help staff immigration desks and minimize the disruption to incoming travelers.

The government — eager to avoid any disruption as visitors descend for the July 27-Aug. 12 games — is hoping that many staff turn up for work despite the walkout. Only 20 percent of union members voted in the strike ballot.

The union said its members also will take other forms of industrial action, such as a ban on overtime from July 27 to Aug. 20 — what is expected to be one of the busiest periods ever for London’s airports.

In more transit trouble, about 400 train workers have threatened to strike for three days in central England during the Olympics in a pension dispute. Drivers for East Midlands Trains said Thursday the strike would be from Aug. 6 to 8.

The strikes could be highly disruptive to the games — Olympic soccer matches are being held across the U.K., many workers and Olympic tourists are coming from outside London and thousands of spectators are likely to use trains to get to venues around the capital.

British public sector workers have held a series of strikes in a largely unsuccessful bid to derail government spending cuts. Cameron’s Conservative-led administration is aiming to slash the budget by 80 billion pounds ($130 billion) by 2015 in a bid to curb a deficit swollen by the global financial crisis.

The strikes are the latest in a long list of pre-Olympic glitches. Officials have had to scramble to plug security gaps for the games, after contractor G4S admitted it would not be able to provide the thousands of guards it had promised. Some 3,500 troops have been drafted in at the last minute, bringing the number of military personnel involved in the games to 17,000.