General Motors Co. said it intends to file its South Korean unit for bankruptcy if its labor union fails to agree on a restructuring plan that needs to be outlined within the next four weeks, putting pressure on employees and the government to help it stay afloat in the country, Bloomberg News reported. Barry Engle, GM’s international chief, told union leaders yesterday that the company needs employees’ support by the end of this month, a spokesman for GM in Seoul said. April 20 is the deadline for GM to submit its turnaround proposal to the government, and the company is seeking a tentative agreement with unions well before that, the spokesman said. GM is seeking concessions from the union to revive its South Korean business that’s been hurt by mounting losses. In February, GM offered a $2.8 billion new investment plan to turn around the unit over the next 10 years following a threat to exit the country entirely.