A Paraguayan opposition politician who recently publicly critized violations of human rights in his country, disappeared yesterday afternoon at a busy intersection in downtown Asuncion in what his supporters said was a kidnaping arranged by the government.

Domingo Laino, first vice president of the Authentic Liberal Radical Party had been in Washington to testify before the Organization of American States' annual meeting in late June.

A spokesman at the Paraguayan Embassy, while acknowledging that something had happened to Laino, disclaimed government responsibility for his disappearance.

"We are very worried about him," said Juan Albertso Llanes of the embassy.

According to a friend here who talked yesreday to Laino's wife in Aucunsion, Laino was siting in a car at 3.30 p.m. at the corner of Mariscal Lopea and Peru boulevards when two men in a Volkswagen pulled up and forced Laino out of his car. They reportedly began to beat Laino, then shoved him into their car and sped away.

Laino had just returned to Paraguay after six-week stay in the United States where he had met with many congressman and high-level State Department officials after scoring the Paraguayan government of Gen. Alfredo Stoessner for human rights violations. yesterday morning, he called the Washington Office on Latin America, which had sponsored his trip to the United States to inform them of his safe arrival.

Joe Eldridge of the Washington Office on Latin America, a church-funded group, said that he believes Paraguayan authorities were responsible for Laino's disappearance.

"It would be virtually impossible for a politician of his stature to be abducted without official sanction," Eldridge said. "But I am surprised because he was so prominent at the OAS meetings. It happened so quickly," he added.

A State Department official confirmed "that something had happened" to Laino, but declined to characterize it as a "kidnaping."

"He was picked up. We don't know what happened to him," the official said.

"There have been calls from all over the Hill," he said. "There is a tremendous amount of pressure and outrage. We'll go in to the Paraguayan government and asked them what happened."

paraguay, which has been under the rule of Stroessner since 1954, often has been accused of torture and illegal detention of Indiansand political dissidents by groups monitoring human rights.