An 11th hour legal bid to prevent a strike by border staff on the eve of the London Olympics tomorrow is being sought by the government.

The Home Office believes there was a procedural error in the strike ballot by the Public and Commercial Services Union and is attempting to block the walk out in the High Court.

Strike action would hit travellers on the busiest day of Olympic flight arrivals when visitors are expected to flood in to London airports ahead of the opening ceremony.

Home Office minister Lord Henley said the department’s officials were verifying the legality of the threatened industrial action, which was voted in by only 12% of the PCS membership.

“We are currently checking on the legality of the strike and, if satisfied it is illegal, we will take the appropriate remedies in the courts,’’ Lord Henley is reported by the Financial Times as saying.

He added that the strike was “opportunist and wholly unjustified”.

The PCS pledged to would “robustly defend” it actions, saying it hoped ministers would continue negotiating rather than resort to legal alternatives.