The country's largest steelmaker SAIL has said the rails supplied to railways are totally "defect free" and processing of tracks at the PSU follows highest level of quality control. The statement comes in the wake of railways inviting a global tender to plug the shortfall in supply of rails from Steel Authority of India Ltd (SAIL). "Production of rails is a complex multi stage process. The processing of rail tracks at SAIL follows highest level of quality control by virtue of which almost 15 per cent of work in progress is kept aside during various stages of production," a company official said. State-owned SAIL has been its sole supplier so far. The public sector undertaking (PSU) has been supplying tracks to Indian railways for more than five decades. "The 100 per cent of rails supplied by SAIL to Indian railways are inspected by a third party and are completely defect free," the official added.