The tumble in global demand for steel took a heavy toll on trading at Cookson in the first four months of the year, prompting the supplier of ceramic moulds and other consumables to the industry to cut a further 600 jobs.

The company, which in January launched a £240m rights issue aimed at avoiding a breach of banking covenants on its £730m of debt, said underlying revenue in the first four months of the year remained down by a third on the same period in the previous year.