Dutch regulators threatened to close down one of Tata Steel's main ovens at its massive plant in IJmuiden if it doesn't limit pollution within a year. The regulators said Tata's coke oven at the plant continued to operate in breach of environmental regulations and they would consider revoking the licence for the oven if pollution wasn't cut within a year. Coke ovens are manufacturing plants or blast furnaces for making coking coal, a key raw material in steelmaking. Tata has repeatedly said closure of the oven would threaten the existence of the whole steel plant on the Dutch coast west of Amsterdam. Tata's factory in IJmuiden is one of the largest emitters of greenhouse gases in the Netherlands and research has found it is also responsible for a range of health problems in the region. The company's Dutch arm on Thursday questioned the way regulators had measured pollution at the plant and said it had already improved the situation at the oven considerably. It had earlier promised to close the oven once its promises to convert the steel mill to a cleaner one powered by natural gas or hydrogen have been realised by the end of the decade. Tata has been in talks with the Dutch government about subsidies for making this transition for several years, without reaching a deal.