There are growing signs that a substantial number of lawmakers on two congressional intelligence oversight committees are questioning the wisdom of secret US moves against Nicaragua.
Indeed, some members of the Senate Select Committee on Intelligence and the House Permanent Select Committee on Intelligence say they think the Reagan administration may be breaking the law by supporting the anti-Sandinista forces in Nicaragua.
The two committees, whose work is virtually unknown to the American public, hold the key to blocking or facilitating US aid to antigovernment forces in Nicaragua. Should a majority of the 15 committee members in the Senate and 14 members in the House decide restrictions on American support are necessary, that decision would have a strong influence on other members of Congress. And it might put teeth into congressional moves to ban covert operations in Nicaragua, moves that until now have lacked any real authority.
Most senators and representatives know little more than what they read in the newspapers about the intensified fighting in Nicaragua and allegations of US backing for the ''counterrevolutionary'' forces fighting there. So on this issue they tend to defer to their colleagues on the intelligence oversight committees, just as they do on most matters involving secret operations.
Members of the two committees usually don't talk about such matters. But recently the grumbling from some of them has grown audible. Last week, Sen. Daniel Patrick Moynihan (D) of New York, vice-chairman of the Senate oversight committee, publicly complained that the Central Intelligence Agency may not be complying with the law.
Last December, Congress reaffirmed a measure that bars the US from providing support for military activities aimed at overthrowing the Nicaraguan government. Administration officials contend they are complying with the law because, they say, they have no intention of toppling the Sandinista regime. But some lawmakers believe the anti-Sandinista forces that the US has aided - apparently through Honduran intermediaries - aim to overthrow the Managua government and may be moving out of control.
Last december, when liberal Rep. Tom Harkin (D) of Iowa led a move to ban all support for such secret operations, he was in effect co-opted by Rep. Edward P. Boland (D) of Massachusetts, chairman of the House Permanent Select Committee on Intelligence. Representative Boland called on the House to adopt previously classified language from the Intelligence Authorization Act of 1983, which approves funds for the CIA. That language, agreed to by Senate and House conferees in closed sessions last August, stated that no funds authorized by the act should be used to overthrow the government of Nicaragua or to provoke a military exchange between Nicaragua and Honduras.
''Boland's concern was that he was going to lose control over the House,'' said a congressional staff specialist. ''He was trying to head off the Harkin amendment.''
''The members of these committees feel that they have to be super-responsible ,'' said another staff aide, this one in the Senate. ''They don't want to endanger the relationship they have with the intelligence agencies. They don't want to get cut off from information.''
This time around, however, it may be the intelligence committees themselves that initiate further actions to restrict the administration's secret activities in Central America.
The committees don't have the right to veto such operations. But the law requires that they be informed about the operations, and they do have the influence that might be needed to get their fellow legislators to tighten the laws. The committees also have a say over funding for the intelligence agencies.
One congressman who has declined to get any intelligence briefings because he does not want to compromise his ability to speak out on the issue said he is hearing this type of remark from his colleagues on the House oversight committee: ''If you really knew what was going on down there, you'd be more worried about it than you are now.''
There is no love lost for the Sandinistas in Congress. Several lawmakers who have visited Nicaragua over the past year or two found the leaders they met arrogant and hostile. The heckling of Pope John Paul II during his visit to Nicaragua last month made an extremely bad impression on many in Congress.
''So far, people's antipathy in the Congress for the Sandinistas has outweighed their antipathy for covert action,'' said a specialist on one of the congressional staffs that deals with such matters.
Still, concerns that the administration may be violating the law are mounting. Last week, 37 congressmen sent a letter to President Reagan expressing their concern over reports that insurgents operating in Nicaragua were receiving help from the CIA.
''We believe that the current attacks inside Nicaragua are creating a climate in which open hostilities between Nicaragua and Honduras are a distinct possibility,'' the letter said. ''We urge you to act in strict compliance with our domestic legal obligations as well as those embodied in the international charters of the United Nations and Organization of American States.''