President Carter's reelection campaign filed suit yesterday to block the Federal Election Commission from giving $29.4 million in public campaign funds to GOP presidential nominee Ronald Reagan.

The commission has scheduled a pro forma meeting for 10 a.m. today to certify that Reagan is eligible to receive the money.

But Carter forces asked the U.S. Court of Appeals to prevent that until a decision in two suits challenging the legality of independent groups' plans to spend millions of dollars in Reagan's behalf.

The action was the latest move by the Carter camp to thwart the independent groups, which hope to raise more than $40 million.

The Reagan campaign labeled the Carter group's suit "a spurious and underhanded attempt by the Democrats to delay the Reagan-Bush campaign's rightful access to campaign funds."

"It is a sure sign of panic on the part of the Carter-Mondale leadership and the Democratic National Committee that they are trying to disenfranchise half the American people [Reagan supporters] through this suit" campaign manager William Casey said in a statement.

Under federal law, the nominees of the Republican and Democratic parties are prohibited from receiving private campaign contributions and must fund their races with $29.4 million in public money.

The Reagan campaign has been on a shoestring budget for months and is said to be almost broke as it gears up for the fall campaign.

In the suit, the Carter group and the DNC argued that the FEC would, for all practical purposes, lose its ability to enforce federal election law if Reagan is granted the full $29.4 million.

It suggested that the FEC could authorize a partial payment to Reagan until the suits challenging the independent fund-raising groups are settled. One of the suits was filed by the FEC; the other was filed by Common Cause, a self-proclaimed public advocacy lobby.

"Basically what we're asking is for them to make a determination of the law and facts before they make Reagan eligible for the full amount of money," said Tim Smith, counsel for the Carter committee.

The fear in the Carter camp is that the independent groups will enable Reagan to outspend Carter by better than 2 to 1.

The groups base their legality on a 1976 Supreme Court ruling that individuals or committees can spend unlimited amounts for or against candidates so long as they act independently of the campaigns.

Reagan manager Casey said yesterday that his campaign "is in no way involved" with any of the independent groups.

However, Smith said Carter forces are supplying the FEC almost daily with examples of contact between the groups and the Reagan campaign.