Members of a Scottish teaching union are to begin industrial action over changes to their pensions. The Scottish Secondary Teachers Association (SSTA) said members would begin a "work to contract" on Monday morning. The union said its members would not be doing any work beyond their contracted 35-hour week. And it called on teachers to stop "gifting" employers 10 to 15 hours of free labour each week. The SSTA has stressed members will not be withdrawing their labour or closing schools. The dispute centres on the proposed changes to public sector pensions by the UK government, which the SSTA has claimed "amount to an additional tax on public sector workers". Speaking when SSTA members voted in favour of the action last month, a Scottish government spokesman said it was committed to public sector pensions which were affordable, sustainable and fair. He added: "Discussions with trade unions, including SSTA, and employer group representatives on long-term reforms of public sector pensions have begun. "These discussions need to be carefully considered but also mindful of the time constraints we face as a result of the limitations set by the UK government."