MITSUI O.S.K. Lines (MOL) is undecided whether to use mid-stream or terminal services for its new full container service to be carried with Nedlloyd Lines between the Far East and the east coast of South America. An industry source said shippers were asking the joint venture to use mid-stream services as it cut cost by almost two-thirds. ''We cannot comment on this as it is still under negotiations,'' said Hiroyuki Fukumoto, assistant general manager of MOL's Hong Kong operations. But he agreed that the costs of handling containers in mid-stream was much lower than charges at terminals. MOL's other services use Hong Kong International Terminals (HIT) for its boxes. The industry source said the operating costs for handling containers in Hong Kong port was getting higher forcing shippers to look for ways to cut costs. Mr Fukumoto said MOL would triple its service frequency with three sailings per month with a 10-day interval via the Indian Ocean from September 30. MOL is to provide four vessels - Atlantic Challenger, Asian Challenger, Pacific Challenger and another vessel to be chartered - while Nedlloyd will provide the Vega, Petralia, Bellavia, Castor and Corinthiakos. MOL's senior operations manager Patrick Yeung said the service would provide the fastest direct linking Hong Kong to Buenos Aires, in 29 days, Montevideo in 30 days, Paranagua in 35 days, Santos 36 days and Rio de Janeiro 38 days. He said the joint venture was in response to the constant growth in container traffic in the trade.