Representatives of more than 30 religious organizations, unions and public interest groups yesterday attacked a group of Senate budget amendments that would deregulate the broadcast industry extensively.

"All of these reductions in public protection amount to a virtual expropriation of the public airwaves," said consumer activist Ralph Nader at a Capitol Hill news conference. In a joint statement, the groups said that the riders, "if they become law, will eliminate many of the important safeguards for a fair and democratic communications system."

The Senate amendments would grant permanent licenses for radio stations and five-year licenses for television stations, as compared with the regular three-year renewal now required. In another change, regulations requiring radio stations to broadcast public service programming would be relaxed.

Consumer and public interest groups have long argued that the Federal Communications Commission's control over who gets licenses -- and outsiders' ability to challenge licensees -- are the principal ways to force broadcasters to provide public affairs and minority-oriented broadcasting. The groups yesterday said the bills, which were included in the Senate's version of the budget reconciliation bill as floor amendments, would take those weapons away.

"It's the threat of regulation that has caused broadcasters to provide whatever they're providing," said Peggy Charren, president of Action for Children's Television. If the deregulation bills are enacted, she said, "the broadcasters will go back to considering children only as a market, and any success we have had over the last 10 years will be erased."

The organizations represented yesterday -- and many members of the House of Representatives -- are as angered by the way the Senate included the bills in the budget package as they are by the measures' contents.

Donald Matthews, a Jesuit priest representing the National Catholic Conference, denounced "the arrogant manner with which these amendments were added to the budget bill." Nader branded the Senate move an effort at "backdoor deregulation."

Senate Commerce Committee Chairman Bob Packwood (R-Ore.) introduced the measures after his committee heard two days of testimony on the bills.Robert Witeck, as aide to Packwood, discounted charges that the Republican Senate was "rushing" passage of changes favorable to the industry. "We had over 200 hours of hearings on communications issues in 1979. These proposals have been extensively discussed."

Other groups represented at the morning news conference included religious organization such as the United Church of Christ and the Anti-Defamation League of B'Nai B'Rith; public interest groups such as the National Organization of Women and Consumers Union; the National Education Association, a teachers group; and labor organizations such as the AFL-CIO, the United Steelworkers of America and the United Mine Workers International Union.