Supporters of Ronald Reagan yesterday accused President Carter of abusing his powers as an incumbent in the presidential race, and demanded information from 29 government departments and agencies on recent political activities by administration officials.

Republican National Committee Chairman Bill Brock led off the assault at a news conference at which he announced that the RNC was filing 29 Freedom of Information Act requests with government agencies for details of travel and public appearances by officials of the angecies.

Brock cited press reports he said indicated that many of the appearances by administration officials paid for by the government were actually political in nature and designed to further Carter's campaign against Republican nominee Reagan.

"We want to find out to what degree the administration is using the taxpayers . . . to finance their own reelection campaign." Brock said.

Later yesterday, Reagan's campaign chairman, Sen. Paul D. Laxalt (R-NEV.), weighted in what he called the two latest examples of the "continuing and unbridled abuse of incumbency" by the White House.

Laxalt charged that Eula Bingham, head of the occupational Safety and Health Administration, recently asserted that Reagan intended to end OSHA functions and "back off" enforcing its regulations.

Laxalt also accused Sam Brown, head of Action, of suggesting that Reagan opposed the development of solar power.

Both statements were false and "clearly orchestrated and coordinated by the White House of political campaign purposes," Laxalt said.

White House press secretary Jody Powell dismissed the charges as "a quadrennial phenomenon" that always accompanies the reelection campaign of an incumbent president.

Powell also said that Brock's remarks on "abuse of the incumbency" were "not nearly so harsh as Reagan's criticism of the Ford administrations four years ago" on the same subject when Reagan was challenging then-president Gerald R. Ford in the republican primaries.

The White House recently issued guidelines on political activity by administration officials, but they were reportedly softened after objections from Carter campaign committee officials. The guidelines grew in part out of recently issued Federal Election Commission regulations.

Among other provisions, the guidelines require that, when officials make campaign appearances for the president in a city they are also visiting on official business, the entire cost of the stop must be paid for by the campaign committee and cannot be divided, as it was during the primaries, between the committee and the government.

At his news conference, Brock cited a pamphlet issued by the Community Services Administration, a recent trip by Health and Human Services Secretary Patricia Roberts Harris and an "official trip" made by the president as examples of "abuse."

The CSA pamphlet depicts John F. Kennedy, Lyndon B. Johnson and Carter, all Democrats as "people against poverty," with no mention of the Republican presidents under whom the agency has operated.

"It's absolutely inexcusable," Brock said of the document. "If he has reason to be reelected, he should do so on his own record without using the taxpayers of this country."

Brock said Harris' trip to Dallas and Los Angeles on Aug. 5 and 6 was for the purpose of delivering a "clear political speech" attacking Reagan. He said the same was true of the president's visit in July to the National Education Association convention in California, where he delivered a speech with "political content."

"Ted Kennedy was making some fairly effective charges back in the spring," Brock said in references to similar accusations leveled against Carter by Sen. Edward M. Kennedy (D-MASS.) during the primaries. "He was right." s

In making the NEA speech and similar "official" appearances before the start of the general election campaign, the president was always careful not to mention Reagan by name so that the cost of the travel was paid for by the

Both Brock and Laxalt conceded that the kind of charges they made yesterday are a predictable element of campaigns involving incumbents. But they both said the Carter White House was exceeding the normal bounds of using the power of incumbency.