The Polish Catholic Church has asked the European Community for emergency supplies of powdered milk for infants, apparently because of concern about contamination of local milk by radioactivity from the Chernobyl plant, EC Executive Commission sources said today.

In a related development, a commission spokesman said the executive body was not aware of any requests from the Soviet Union to buy extra food from the community, which was reported in London by a British member of the European Parliament earlier today.

A commission source said the Polish request for the free powdered milk from the EC's surplus stocks, made several days ago, was under consideration by the commission. The sources would not say how much powdered milk was requested.

The request was made through a Catholic aid organization that has served as an intermediary for past EC grants of free food aid to Poland, the sources said.

The commission also imposed an immediate ban on imports into the EC countries of fresh meat and livestock from the Soviet Union, Bulgaria, Poland, Hungary, Romania, Czechoslovakia and Yugoslavia.

The ban will remain in effect until the end of May, but EC officials will meet on May 20 to consider whether the prohibitions should be modified.

The commission acted as EC member states deliberated about extending the import ban to all food exports from the seven countries. Italy also was pressing for the ban to be applied to East Germany and Austria, a move resisted by West Germany because of its links to the countries, EC officials said.

The value of EC imports of food from the six Eastern European nations affected by the ban, excluding Yugoslavia, was about $570 million in 1985. Essentials such as meat, milk and grain are produced in abundant surplus inside the 12-nation community.

The commission has proposed to the member states that they agree on a common standard for permissible traces of radioactivity in foodstuffs produced and traded within the community, or exported.

Washington Post correspondent Karen DeYoung reported from London:

Richard Cottrell, a member of the European Parliament, said in a radio interview today, "Information reaching me suggests that the Soviet Union, using diplomatic channels, has approached Brussels with a view to purchasing substantial quantities of surplus community food including grain, butter, beef and skimmed-milk powder."

The European Commission said that it had received no direct request from the Soviets. But a senior official in London said it "is entirely possible" that such a request will be forthcoming.

"There has been no direct approach," the official said, "but that doesn't mean inquiries haven't been made through a trader," one of the independent dealers who trade in surplus community food.

"It doesn't seem unlikely," he said, considering that the contamination is believed to have extended over "a very large and rather productive area of the Ukraine," the Soviet breadbasket.

The community has in frozen storage more than 700,000 tons of meat and 1.2 million tons of butter, in addition to substantial stores of powdered skim milk and frozen whole milk. In terms of immediate requests, the official said, "meat and milk would make the most sense. The cereals would probably come later."

Although some countries, primarily in the Third World, are eligible for special community price subsidies, the Soviet Union would be expected to pay world market rates for the foodstuffs.