The European Economic Community approved yesterday an agreement to reduce export credit subsidies significantly, a move welcomed by the Reagan administration, which had angrily threatened the Europeans for failing to reach an accord.

The agreement limiting controversial export financing packages competitively offered by the world's major industrial nations is "a good compromise and one which we welcome," Assistant Treasury Secretary Marc Leland said in an interview.

The administration has slowly negotiated reductions in export subsidies and has made elimination of all subsidies one of its goals. U.S. Trade Representative William Brock had said he would "personally advocate the use of a 2-by-4 in whatever fashion we could get" to force the Europeans to agree on reduced subsidy levels.

The administration had hoped to sign the arrangement in May, but it was delayed by the French who "never really wanted to go along with it," Leland said. The French have been heavy export subsidizers. "The Germans, Dutch and British basically have been for" the subsidy reductions. Leland said he didn't know what caused the French to change their position.

At issue is the practice of countries providing attractive, low-interest-rate financing to purchasers of goods made by companies in their country. Such subsidies have given foreign firms advantages in contract bidding. For example, the latest export subsidy flap concerned a $700 million contract to a Canadian company for subway cars to New York's Metropolitan Transportation Authority that was subsidized at an interest rate below the one agreed upon by the industrial nations.

The Canadian government said it was coerced into providing the lower interest rate because it had to match a low rate offered by the French.

The arrangement approved at the EEC finance ministers meeting yesterday pushes many countries receiving the low interest rates, such as the Soviet Union, into categories providing higher rates. For example, countries previously defined as developing were moved into the middle-income country category, which has higher interest-rate levels.

Some countries in the middle category were moved to advanced-country status, prohibiting them from receiving the lower rates, administration officials said.

The interest rates allowed under each of the categories also were increased, administration officials said. In addition, the Europeans have agreed to a provision that would prohibit any country from violating the subsidy levels, such as in the Canadian subway car case, Leland said.

Previously, a country providing financing contrary to the arrangement could offer the package as long as it announced its intentions, allowing other countries to match the deal, Leland said.

The administration hadn't accepted the agreement officially yesterday, but was expected to later, Leland said.

The first major agreement in subsidy reductions was reached last October, and gains made in the new agreement are comparable to those reached last fall, Leland said.

The next meetings to reduce subsidies further will be held next year, Leland said.