Werner Rothfuss, a BMW spokesman, said that local conditions in South Carolina were 'not suited' to trade union activity and that the company wanted to deal directly with the workforce there.
'We do not need the interference of a third party or a trade union in the process,' he said.
He conceded, however, that if the workforce, which should eventually number 2,000, elected to work under the umbrella of a union, the company would probably not block it. 'We will, of course, comply with the local laws,' he said.
The dispute over the new BMW plant, which was announced in June, erupted last week. In a terse letter to Eberhard von Kunheim, BMW's chairman, Klaus Zwickel, IG Metall's deputy president, said that the union would fight to ensure that employees at the plant would be allowed to organise themselves under union protection. IG Metall plans to work closely with the United Automobile Workers union in the US during the construction phase of the plant, which starts next year.
Dagmar Opoczynske, an IG Metall spokeswoman, said: 'We have a history of forcing German firms who set up abroad to work with local unions and we do not intend to make an exception here. If BMW was allowed to get away with it in South Carolina, they would try it on everywhere.'
South Carolina is a so-called 'right-to- work' state with one of the lowest rates of unionisation in the US. In Germany, BMW's labour costs, including benefits, are about 43 marks (about pounds 15) an hour; in South Carolina, they will be at least one- third lower, analysts say.
In Germany, BMW would be unable legally to exclude unionisation in a new factory or to bar union representatives on oversight committees which have power to influence company policy.
Dan Stillman, spokesman for the American car workers' union, said BMW was creating a double-standard by opposing unionisation. The company works with unions everywhere else it operates and 95 per cent of American car assembly plants are unionised.
'It's irrational,' said Mr Stillman, 'It's one thing to have lower costs than in Germany, but another to have them lower than the rest of the US industry.'
The only big non-union factories in the US are three Japanese 'transplants' operated by Honda, Nissan and Toyota. Volkswagen co-operated with the union when it opened an assembly plant in Pennsylvania in 1979, but closed it after its US-made cars won a reputation for poor quality.
More recently, Freightliner, the heavy truck division of Daimler-Benz attempted to circumvent unionisation when it opened a factory two years ago in North Carolina. But the UAW, with the help of the trade union at Mercedes, eventually won the right to represent the workers and negotiated 'an excellent contract' with the German owner, according to Mr Stillman.
'We fully intend to organise the BMW plant in Spartanburg,' he said.
BMW hopes to be producing more than 300 cars a day at the plant from 1995, eventually employing 2,000 workers. The company says its main aim is to boost its sales in the US which, having reached almost 100,000 in 1986, slumped to 53,000 last year.