Union workers at Hyundai Motors in South Korea said they intend to boycott an extra weekend shift to participate in a rally that opposes the free trade pact with the US.

The union said they would attend the national workers rally organised by the Korean Metal Workers’ Union scheduled for 20-21 November in Seoul.

Managers at the automaker’s Ulsan plant said the decision to boycott extra weekend work shift would cost production of 7,600 vehicles.

However, at Hyundai affiliate KIA and GM Korea, only union leaders are expected to take part in the rally.

The free trade agreement is still pending approval from South Korea.

It was signed in June 2007 and in December 2010 was modified in regard to the auto industry.

The agreement was ratified by the US Congress in October 2011.

Policymakers in Washington and Seoul are urging the governments to implement the FTA starting on 1 January.