FRANKFURT (Reuters) -- Volkswagen's senior labor leader gave his blessing to management plans for a possible new engine and transmission factory in North America to supply the carmaker's upcoming U.S. assembly plant.

"A localized supply of parts is necessary with a capacity of between 250,000 to 300,000 vehicles. So one should also consider building a new engine and gearbox plant," VW works council boss Bernd Osterloh told reporters in Wolfsburg in comments embargoed for today.

Management, which expects to decide where to break ground on a new U.S. car plant before the summer break in July, has said it would like to have a very high level of localization for the new site, with about 80 percent of models built there sourced in the dollar area.

Any decisions to start building a new production plant have to be approved by labor leaders like Osterloh, who comprise half of VW's supervisory board.

"It's not been decided where the site might be located," he continued, adding that not just the United States but also Mexico remained an option, where VW already builds engines in its Puebla plant.

The carmaker manufactures transmissions in its Cordoba site in Argentina as well.

Osterloh, who also sits on the supervisory board's influential six-person steering committee, said ownership issues related to Volkswagen's stakes in European truckmakers MAN and Scania were of secondary importance.

"The main thing is that we can leverage synergies between the truck businesses of Volkswagen, Scania and MAN," he said, declining to comment further.