Agriculture Secretary John R. Block warned the European Economic Community yesterday against its use of export subsidies and other "trade-distorting practices."

Block also told reporters during a break in his testimony before a House Ways and Means subcommittee that he is noticing a trend in various U.S. agricultural industries to seek protection against European export subsidies. Already the flour, pasta, sugar and poultry industries have asked for relief from what they call unfair trading practices by the Europeans. The Agriculture Department is supporting the poultry industry in its recent complaint, Block said.

"We are particularly disturbed over the EEC's increasingly aggressive use of export subsidies and their proposals to establish a formal Common Export Policy," Block said. "This policy would use long-term bilateral agreements, special credits and an even greater use of export subsidies to dispose permanently of surplus production in international trade. We have told EEC leaders that we cannot and will not accept trade-distorting practices."

Block said American farmers also are getting increased competition from major exporters in South America and Europe, "and this was stimulated, if not generated, by the Soviet embargo," which gave other producers a crack at the Soviet market.

But Block said "a greater threat and a bigger challenge to U.S. agricultural export growth is the rise in protectionist sentiment in the trading world."