The congressional battle over aid to the Nicaraguan rebels heated up yesterday as House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.) accused the White House of betraying an understanding it had reached with him.

As a result, O'Neill appeared to be hardening his insistence that a scheduled House vote next week on a $100 million aid package for the counterrevolutionaries, known as contras, be part of the consideration of the 1986 supplementary appropriations bill.

The dispute involves more than parliamentary tactics. The Reagan administration and its allies on Capitol Hill are arguing that to attach the package to the appropriations bill -- which could take months to enact and might ultimately be vetoed by President Reagan -- would effectively kill aid to the contras.

At his news conference last night, Reagan voiced this concern. "This proposal [the contra aid] must not be held hostage to any other legislation," he said in promoting the aid.

Both the House Republican leadership and a group of moderate to conservative Democrats who have drafted an alternative contra aid package are pressing the Democratic leadership for a separate vote on the issue. But a House Democratic leadership aide said he did not expect O'Neill and other House leaders to back down on the issue.

O'Neill said that following last month's incursion into Honduras by the Nicaraguan Sandinistas, White House chief of staff Donald T. Regan assured him that the administration would not link the incursion with the House vote on March 20 rejecting the aid package.

In the same conversations, O'Neill said, he pledged to search for "a different vehicle" than the appropriations bill for the second contra aid vote that is set for Tuesday. But two days later, he added, the president went to New Orleans, where he charged that rejection of the aid package had sparked the Honduran incursion.

"There are no obligations to anyone," O'Neill said. "The vote will be on the supplemental."

At the White House, Dennis Thomas, the top aide to Regan, confirmed that these subjects had been discussed but denied that any understanding had been violated.

"We have gone out of the way to take partisan rhetoric out of our statements," he said.

The House Rules Committee is scheduled to meet today to set the ground rules for the contra aid debate on the House floor next week. Officials indicate the committee is likely to approve a separate vote on the contra bill; a separate vote on the spending bill, but the two would then be automatically joined if approved and sent to the Senate. The result of that action would mean Reagan would either have to accept the supplemental part of the package, which contains numerous provisions to which he objects, in order to get the contra aid, or veto the legislation.

The administration is seeking $70 million in military aid and $30 million in nonlethal "humanitarian" assistance to the contras, who are fighting to overthrow Nicaragua's Sandinista government. Seven days after the House rejection of this package, the Senate narrowly approved a slightly modified version of the measure.

The Senate-passed bill would delay release of $75 million of the aid for 90 days while the United States sought a negotiated settlement to the conflict. The $25 million that would be available immediately could be used for military training and acquisition of "defensive" weapons, including surface-to-air missiles.

If negotiations failed, the $75 million in remaining aid would be released unless blocked by a congressional resolution disapproving it. This, however, would be subject to a veto by Reagan.

In next week's second showdown in the House, Republicans are expected to offer an aid package that closely parallels the Senate measure while liberal Democrats push a resolution that would provide no aid.

Meanwhile, a group of moderate to conservative Democrats have reached general agreement on a third alternative, according to Rep. Dave McCurdy (D-Okla.). He said this plan would also delay release of $75 million in aid for 90 days, but would require an affirmative vote by Congress before it could be used.

McCurdy said he wants a separate vote on contra aid. "I don't want it muddied," he said. "I want a vote on the merits."

The administration argues that any of these alternative aid plans will be useless if they are attached to the supplemental appropriations bill, which some officials said could well be vetoed.

Meanwhile, a House Foreign Affairs subcommittee voted to demand that the White House provide all available documents on its spending for contra supplies out of the United States. The resolution of inquiry, which must be approved by the full House, is a response to testimony by the General Accounting Office that it could not verify the spending of $7.5 million of last year's $27 million program of nonlethal aid to the contras.

In a letter to the subcommittee, the Reagan administration promised to provide some documents but not all those requested.