The Commerce Department and two senior Democrats of the House Commerce Committee have strongly criticized an Internet search service being planned by Network Solutions Inc., saying the company is blocking potential competition.

The statements fuel a growing dispute between Network Solutions and the government over ownership of a data bank of Web address registrations and the larger issue of ending the company's monopoly over Internet address registration.

The new service, the Dot Com Directory, draws on a database that Network Solutions has compiled as the monopoly assigner of more than 5 million addresses that end in ".com," ".net" and ".org." The company says the service will help people find business Web sites without having to sift through irrelevant search results that they often get from popular search engines such as Yahoo and AltaVista.

While the company asserts it has intellectual-property rights to the information, the Clinton administration and members of Congress have insisted that the database belongs to the public.

On Friday, Democrats John D. Dingell (Mich.) and Ron Klink (Pa.) wrote to the Commerce Department requesting that it to look into the competitive implications of the directory. It is "a very troubling development by a company in a monopoly position that already appears very reluctant to give up that position," the letter said.

In a letter to the company sent on the same day, Commerce Department general counsel Andrew J. Pincus said that "we strongly object to NSI`s restrictive policy" concerning access to the database by other companies. The letter specifically asked the company to open its database to other companies.

"The announcement of the `Dot Com Directory' highlights the importance of addressing this issue quickly," the letter said.

In a phone interview yesterday, Network Solutions spokesman Chris Clough said the company is reviewing Pincus's letter, but doesn't believe the controversy will affect the launching of the new service, which is scheduled for later this week.

So far, House representatives haven't proposed legislation to force Network Solutions to make its data bank available to competitors. Dennis Fitzgibbons, Democrat spokesman of the Commerce Committee, said committee members are likely to let "legal proceedings run their course first."