A Grenadan diplomat yesterday delivered an emotional and blistering attack on the invasion of his country, telling the Organization of American States that the United States is "deliberately lying" about its reasons for "unleashing terror and death on the people of Grenada."

Fifteen of the 28 member countries present, from Mexico to Argentina, joined Grenada in condemning the invasion and urging the United States and six Caribbean nations to withdraw their troops immediately. However, the OAS considered no resolutions on the subject last night.

Ian Jacobs, Grenada's alternate delegate to the OAS, blamed the United States for what he called "massive casualties" in his country and said reporters had been barred from the island to "hide the atrocities" there.

"Blood will drip from the fingers of the United States when the truth comes out about what has happened in Grenada," Jacobs said. "It is an international outrage. Today Grenada, but ask yourselves, who is next? Who is next that the United States does not like . . . ?"

Jacobs said his government had sent a telegram to the U.S. Embassy in Barbados two days before the invasion, insisting that American citizens on the island would not be harmed and were free to leave. "It is very clear that this smoke screen of danger to American students was a complete fabrication," he said.

Jacobs also said the military regime that took control of Grenada last week had been planning to yield power to a civilian government to be formed in 10 to 14 days.

Mexico, the Bahamas and the Dominican Republic joined a number of South American nations in accusing the United States of violating the OAS charter. Mexican Ambassador Rafael de la Colina said the invasion would leave "deep and persistent wounds." Colombian Ambassador Francisco Posada de la Pena likened the U.S. action to the Japanese attack on Pearl Harbor, saying the invasion had reduced the OAS charter to "empty words."

Bahamian delegate Reginald Wood called the invasion "a cruel act of intervention" and said the United States had exhibited "a double standard of international morality."

The other nations criticizing the invasion were Nicaragua, Peru, Bolivia, Venezuela, Ecuador, Panama, Brazil, Paraguay, Chile and Trinidad and Tobago.

Only the six eastern Caribbean nations who contributed troops to the invasion defended the action. Delegate Donatus St. Aimee of St. Lucia called the landing "a preemptive defensive action" that was "well within the legal constraints" of OAS regulations.

U.S. Ambassador J. William Middendorf II also strongly denied that the action violated OAS charter restrictions, calling the invading troops "a collective security force" responding to an appeal from Grenada's neighbors to prevent further violence on the island.

"Such humanitarian action has long been recognized as consistent with international law," he said.

Earlier, Prime Minister Eugenia Charles of Dominica told the OAS that a military buildup in Grenada had "posed a serious threat to the security" of her nation and its neighbors. She said she had feared that Grenada would "be used as a staging post for acts of aggression" in the region and that what Cuba has referred to as "construction workers" in Grenada actually were soldiers.

Charles said the British governor general in Grenada would seek to hold new elections. But she said that former Grenadan prime minister Eric Gairy "and other undesirable political elements . . . would not be welcome in Grenada."

Grenada's Jacobs ridiculed suggestions that the Cubans in Grenada were military personnel. Citing previous U.S. military exercises in the Caribbean, he accused the United States of "a step-by-step determination to overthrow" the military government that took control of Grenada in 1979.

The 30 delegates also heard a tape from Grenadan Ambassador Dessima Williams, who is reported in hiding. She said the United States "must be condemned for its flagrant and barbaric act" and that history would call the invaders "butchers." graphics/photo: Prime Minister Eugenia Charles of Dominica speaks at the OAS meeting as Secretary General Alejandro Orfila looks on. UPI