France braced for new strikes and mass demonstrations against a deeply unpopular pensions overhaul on Tuesday, a day after lawmakers started debating the contested bill. President Emmanuel Macron made the reform the heart of his re-election campaign last year, and is determined to implement it despite fierce opposition from the political left and unions, but also the wider public. Tuesday's protests are the third such nationwide rallies organized since the start of the year, AFP said. Last week's demonstrations brought out 1.3 million people across the country, according to the police, while unions claimed more than 2.5 million people took part. Either way, they were the largest such protests in France since 2010. Trains and the Paris metro are again expected to see "severe disruptions" on Tuesday, operators said, with around one in five flights at Orly airport south of the capital expected to be cancelled. "We're counting on there being rallies so that the country's elected representatives take into account the opinion of citizens," Philippe Martinez, leader of the hard-left CGT union, told the France 2 broadcaster on Monday. More marches are planned for Saturday, although unions for rail operator SNCF said they would not call for a strike at the weekend, a holiday getaway date in some regions. Macron's proposal includes hiking the retirement age from 62 to 64 years old -- still lower than in many European countries -- and increasing the number of years people must make contributions for a full pension. His ruling party is hoping to pass the bill with the help of allies on the political right, without having to resort to controversial executive powers that dispense with the need for a ballot. But members of the left-wing opposition are staunchly opposed, and have filed for thousands of amendments. - 'Reform or bankruptcy' - Members of Prime Minister Elisabeth Borne's government struggled to defend the overhaul as necessary in parliament on Monday, with many in the lower house booing. As pressure grew, Borne on Sunday offered a key concession, saying people who started work aged 20 or 21 would be allowed to leave work a year earlier. But the head of the CFDT union, Laurent Berger, dismissed the offer as a mere "band aid" -- not a response to widespread public criticism. Macron aims to lift the pensions system out of deficit by 2030 by finding around 18 billion euros ($19.5 billion) of annual savings -- mostly from pushing people to work for longer and abolishing some special retirement schemes. "It's reform or bankruptcy," Public Accounts Minister Gabriel Attal said in parliament on Monday. But critics say that women will on average have to wait longer for retirement than men, as many have interruptions in their careers from childbearing and care responsibilities. Opponents also say the reform fails to adequately account for people in physically strenuous jobs like builders and does not deal with companies' reluctance to hire and retain older workers. Borne claimed the government would pile pressure on companies to end the practice of letting go older employees, which leaves many struggling to find work in their final years before pension age.