France demanded Thursday that the European Commission delay ratification of an international agreement on eliminating shipbuilding subsidies until after it is approved by the U.S. Congress.

Bernard Pons, French transport minister, said Thursday that France will signal its opposition to the deal because of the uncertainty surrounding its adoption in the United States."We do not want to be locked into a system and obliged to adhere to the international accord when others aren't," Mr. Pons said.

There has been strong opposition in Congress to the agreement, which is opposed by the largest U.S. shipyards. The U.S yards say the agreement would prevent them from receiving the government help they need to make the transition to commercial construction from the Navy work they have long been dependent on.

The agreement to eliminate shipbuilding subsidies was negotiated at the Organization for Economic Cooperation and Development among the United States, the European Union, Japan, South Korea and Norway. It is scheduled to enter into effect Jan. 1, 1996.

France had opposed the signing of the deal, but then agreed after it was promised a special compensation package for its shipyards. But the country's shipbuilding industry remains virulently opposed to the deal and would be happy to see it fall apart in the United States. Mr. Pons said France was also assured by the commission that it would delay ratifying the pact until after the United States had done so.

Mr. Pons also announced Thursday a series of measures aimed at turning around the country's struggling maritime industry. In a decision which has been long-awaited by French shipping companies, the government announced it

plans to adopt a system aimed at encouraging private investment in shipbuilding.

Under the plan, the government would put in place a series of tax incentives for private investors who put up capital for the construction of ships. The French government plans to model its system after a German scheme. Mr. Pons said estimates of the cost to the government of such a system are as high as 1.3 billion francs ($260 million) annually.

According to French officials, the government will try to find a way to adapt its system so ships are built in French yards. They said there are ''windows of opportunity" so that such measures would not run contrary to European trade rules or international treaties.

One official said that under the German system, 80 percent of the 100 vessels built annually from domestic private investor capital are to be constructed in German yards.

Among the other measures adopted by the government is an extension of government aid for repairs and modernization of French-flagged vessels.

The cap on the age of ships eligible for the aid will be lifted, to 15 years from 10 years, while the sum allotted by the government will be increased, to 15 percent from 10 percent for investments of less than 80 million francs ($16 million) and to 12.5 percent for investments between 80 million to 120 million francs ($16 million to $24 million).

In order to increase traffic at French ports, the government also announced the simplification of tax formalities and other declarations at ports.

According to an estimate published yesterday, French ports lose out on traffic worth 100 billion francs ($20 billion) to Europe's northern ports