Sofrana Unilines SA, a French-owned company based in Australia, has acquired a 50 percent share in Australia New Zealand Direct Line from New Zealand Line.

In an unusual twist, however, New Zealand Line has the option to buy back half of the 50 percent ANZDL stake in December 1990 at a predetermined price.

Purchase terms were not disclosed.Sofrana said it acquired the ANZDL stake because it wanted to boost its presence in the Pacific Rim and because the opportunity presented itself. Currency changes have led to an increase in European acquisitions in recent years.

Michel Laveau, director general of Sofrana, said in an interview his company does not plan to change ANZDL's management, staff, routes, conference status, agencies, intermodal relationships or company philosophy.

He said the new company will have a more daring approach, however.

Charles H. Speight, managing director of New Zealand Line, said in a telephone interview from Wellington that Sofrana indicated during negotiations that it wanted control to reorganize the tonnage in the trade.

It gives the new owners the ability to come in fast, he said. They're doing quite a lot of adventurous things.

Mr. Speight also said the 20-month hiatus will allow his company's shareholder - the New Zealand government - time to explore privatization proposals for New Zealand Line.

New Zealand Line will be keeping a close eye on the North America trade, he said, and has every intention of returning.

Unless the U.S. economy just goes berserk, we'll be back, he said.

Michael Beard, president and chief executive of ANZDL, said the U.S.-Australia-New Zealand trade can expect steady, if unspectacular, growth for the foreseeable future. He said the line is profitable and expects to be able to fund capital requirements out of existing cash flow.

ANZDL operates a 14-day service between Oakland, Long Beach, Melbourne, Sydney, Brisbane and Aukland that soon will be a 10-day service. The company, which does not post its results, has revenue in the $110 million range.

The deal between Sofrana and New Zealand Line, which technically involves the transfer of Australia New Zealand Container Line, a holding company, was

put together within two months. Two other undisclosed parties were reportedly interested in the ANZDL stake.

Competitors on the trade said it was too early to tell what effect the changes would have on the market.

Sofrana actually has bought into ANZDL from two different directions (see chart). The company announced last week that it had purchased 50 percent of Pacific Australia Direct Line with Compagnie Generale Maritime taking the other 50 percent.

Because PAD in turn owns 50 percent of ANZDL, this will in effect give Sofrana a 75 percent stake and CGM a 25 percent stake in ANZDL. Assuming New Zealand exercises its buy-back option in 1990, ANZDL then will be held 50 percent by Sofrana, 25 percent by CGM and 25 percent by New Zealand Line.

To further complicate the ownership structure, Sofrana itself is 45 percent owned by Delmas-Vieljeux, France's largest private-sector shipping company, and 55 percent owned by private investors.

Mr. Laveau said the 20-year-old Sofrana would not have made the ANZDL

purchase without the support of the 100-year-old Delmas.

It's like the older lady getting in bed with the younger man, he said.

He added that Sofrana tends to act more as the ship operator and Delmas as the owner. Sofrana is running Delmas' interests in the Pacific.

Sofrana is highly profitable, Mr. Laveau said, and financed the ANZDL transaction with its own capital. As a privately held company, it does not post its results. He said Delmas currently has annual profit of $20 million on revenue of about $700 million.

The two French companies' interest in ANZDL stems in part from their existing ties to the French territories of the South Pacific. This is the first time either company has been in a U.S. trade route or one with an intermodal service.

Delmas historically has been involved in trade between Europe and the West Coast of Africa. In the last two years, however, it has acquired two French companies in order to reduce its Africa risk - the NCHP shipping company, which links Europe with the Middle East and the Indian Ocean, and Chargeurs, which serves the Far East, West Africa, the Mediterranean and the French Caribbean islands.