The Carter administration yesterday said it will investigate the import practices of steelmakers in seven European countries charged last month by U.S. Steel with dumping their products in U.S. markets.

The Commerce Department last night said that it had "found sufficient basis in the complaints filed by U.S. Steel" to investigate the companies.

For the past few months the administration has attempted to dissuade U.S. steelmakers from filing dumping complaints against U.S. allies, because they could lead to an increase in international tensions. And Commerce Secretary Philip M. Klutznick, last night, emphasized the administration's hope that the complaints of the nation's largest steelmaker can be solved by other means.

"There are serious problems affecting the industry," Klutznick said. "The administration remains open to pursuing any of the legal alternatives to find solutions in genuine cooperation with industry, labor and our trading partners."

The whole steel issue is sensitive partly because the U.S. is trying to gain cooperation from countries named in the complaint on its problems in Iran and with the Russians in Afghanistan. The issue came to a head last month when U.S. Steel filed complaints against France, Belgium, Luxembourg, Italy, the United Kingdom, the Netherlands and West Germany. l

The complaints were filed after the administration refused to raise steel trigger prices during the second quarter, an action seen as inflationary.

The two-year-old trigger price system is intended to automatically result in a government investigation that can result in stiff duties against the foreign producers if their products are imported below the trigger price for a particular product. The price is based on the cost of production by the most efficient steel producer -- Japan.

The administration had threatened for months to suspend the trigger prices if any antidumping complaints were filed. Shortly after the U.S. Steel case began, the administration suspended the trigger prices.

Klutznick said yesterday that U.S. steel "chose to pursue its dumping complaint through the filing of these antidumping suits. An alternative remedy was and remains available under the trigger price mechanism. The administration is open to either alternative."

The administration's action yesterday is similar to a showing of probable cause in a criminal trial, a Commerce official said. The ruling allows investigators to determine whether the Europeans have shipped steel products to the United States at prices below their fair value.

The International Trade Commission will decide 24 days from today whether the U.S. steel industry has been injured by steel imports.

In addition to initiating the investigation, Klutznick said he has created a special steel task force under his personal supervision to investigate the U.S. Steel case and monitor developments in the international steel trade.