Holland America Line, which until recently said that any newbuildings were not imminent, has announced a principle agreement with Bremer Vulkan for the construction of two new 1,876-passenger cruise ships for delivery in April 1991 and April 1992.

The contract value is $540 million and the transaction will be completed after financing arrangements have been finalized.

In a prepared statement, Nico Van der Vorm, Chairman and Chief Executive Officer of the cruise line, said that "the new Holland America Line ships will be built with the same style and atmosphere we developed for the Nieuw Amsterdam and the Noordam - a style which sets out product apart from present-day ships in the seven-day market."

HAL will also introduce its fourth cruise ship with the Nov. 13 sailing of the 1,120 passenger Westerdam, formerly the Homeric. By 1992, the line will have a capacity of about 9,300 berths.