Long lines snaking through airport immigration halls, hospital operating theaters empty, thousands of schools closed - Britain's government warned Saturday that plans for the country's largest strike in decades could lead to tougher laws on industrial action, AP reported. As many as 2 million public workers are expected to join a one-day walkout on Wednesday, with airlines warning passengers arriving at London's Heathrow and other airports could face 12-hour delays at immigration halls as U.K. Border Agency staff join the action. Teachers, garbage collectors, construction workers and some medical staff are also among those who will strike in an escalating row over planned changes to public sector pensions. The walkout is expected to top the scale of Britain's 1979 strikes - when tens of thousands of people halted work over pay disputes. Some labor unions claim the action could even eclipse Britain's 1926 general strike, when about 1.75 million people joined walkouts. In the latest dispute, workers oppose government demands that they work longer before receiving a pension, contribute more money each month and accept a pension calculated using their average career salary, rather than their final salary. Ministers insist that Britain has no option but to reform its pension system because people are living for longer, and because the gap between contributions and pension payments is growing. Cabinet Office Minister Francis Maude was quoted as telling the Daily Telegraph newspaper on Saturday that the strike - which the government claims could cost Britain's economy as much as 500 million pounds ($770 million) - would be "stupid and wrong." He claimed the fact that some of the labor unions involved have the support of less than 50 percent of their members undermines the case for the walkouts. Britain's government says thousands of operations and medical appointments have already been canceled in anticipation of the strike, with about 400,000 nurses, paramedics, physiotherapists and support staff expected to join the action - though the country's three main medical unions are not taking part. Civil service staff - including workers at Prime Minister David Cameron's office - and contractors will be drafted in to cover for striking immigration officials at Britain's borders, though most airlines have advised passengers to reschedule any journeys planned for Wednesday. The lines at Heathrow's immigration counters are expected to be so long that passengers will need to be held on planes, airport operator BAA has warned. Treasury minister Danny Alexander has urged labor unions to accept a deal proposed by the government, which includes some concessions for low earners and those within 10 years of retiring. -- SPA