Some 1,000 workers at Daewoo Motor’s main plant walked out Tuesday to protest against the arrest of their union executives, labour union officials said. An official for the company said the walkout had stopped production at its main plant at Puchon, west of Seoul.

Early in the morning, police stormed Daewoo’s main plant near Seoul and took 20 unionists into custody, the union official said. A Puchon police spokesman said seven unionists were being held for obstruction of duties – a charge referring to leading workers off the job – and the others had been released.

Workers at Daewoo walked out for 10 days in early April, and unions at other carmakers such as Hyundai Motor followed suit, to protest at plans to sell Daewoo through an international auction later this year. General Motors and Ford Motor of the US are among those which have expressed interest in Daewoo, along with Hyundai, Fiat and DaimlerChrysler.