The four Contadora nations sent to the U.N. Security Council today the treaty they have drafted to end armed intervention in Central America and expressed confidence that "last-minute adjustments" can accommodate objections of the United States and its regional allies.

The foreign ministers of Colombia, Mexico, Panama and Venezuela made public the text of the 51-page treaty draft and predicted that after final "harmonization" in coming weeks the document will win broad international acceptance.

Foreign Minister Isidro Morales Paul of Venezuela said the "polishing and touching up" now envisaged will seek to strengthen verification provisions and make "more orderly" the timing of actions required of the Central American signers.

The State Department Monday expressed its reservations about these and other provisions. The foreign ministers of the Contadora nations, so known because their first meeting was held on Panama's Contadora Island, said suggestions for improvements have been made by Honduras and El Salvador but nothing official has been received from the United States.

In a surprise move, Nicaragua announced two weeks ago that it is willing to sign the current treaty draft, designed to stop foreign military intervention of all sorts in the region. At that point the United States, which had often extolled the Contadora process as a key feature of its Central American policy, began to express strong reservations.

Today's letter by the Contadora foreign ministers to the Security Council, enclosing the draft treaty that resulted from 20 months of negotiations, was described as a means of keeping the U.N. body informed.

Informed sources said this was a substitute for a full-scale U.N. debate on the subject being pushed by Nicaragua to air charges that the United States is waging an undeclared war against the leftist government in Managua and is sabotaging the Contadora effort.

As described by the Contadora ministers, the countries involved will have until Oct. 15 to submit comments on the treaty draft that was made public today. After that, a "political phase" is to be begin when the drafting nations seek to gain final agreement of the political leaders of the Central American states.

It was not made clear when or how the "harmonization" process will take place to make changes in the treaty draft.

State Department officials expressed satisfaction that the Contadora ministers left the way open for last-minute changes advocated by the United States, including precise details on verification and implementation. One official said a meeting involving face-to-face discussion among all the Latin American nations involved might be necessary.

Panama's Foreign Minister Oyden Ortega said, "We feel that the comments on possible changes will be in the spirit of the norms which already exist. We feel the final effort at harmonization will not be particularly difficult."

When the treaty is signed, a two-page protocol pledging full support and promising not to take actions to thwart it will be open for signature by various concerned nations, including the United States. The Contadora ministers said they were assured last week by Western European foreign ministers, who attended a meeting in Central America, that their nations will quickly sign.

The proposed treaty, which is officially titled, Contadora Act for Peace and Cooperation in Central America, includes sections on political and human rights and election processes as well as the more celebrated and detailed military-related provisions.

Among other things, the draft treaty calls for mutual reductions in arms, troops and foreign military advisers by Central American nations and prohibits the establishment of foreign military bases. A key provision bars countries from providing support to irregular forces seeking to overthrow governments in the area, which would prohibit Nicaraguan aid to Salvadoran guerrillas or U.S. aid in Central America for the contras, or counterrevolutionaries, fighting the Nicaraguan government.