President Ferdinand Marcos' sweeping arrest order in the Manila bombing cases was sharply criticized by his opponents today as an overreaction attributable to his own embarrassment at the latest explosion, during an international convention at which he was the featured speaker.

"I think Mr. Marcos overreacted simply because the bomb exploded in his presence," said Salvador Laurel, an asemblyman and former Marcos ally who has recently joined a united front of the president's opponents.

His view was echoed by Liberal Party President Gerardo Roxas Jr., who said Marcos had been placed in an "embarrassing position" when a bomb exploded Sunday at a convention of the American Society of Travel Agents where he had just finished a speech ridiculing past bombings as the result of "fantasies."

Authorities tonight reportedly served an arrest warrant on former senator Jovito Salonga, an opposition leader, but the government appeared to be going slowly in carrying out Marcos' order yesterday to arrest 30 persons allegedly linked to the wave of bombings that began Aug. 22. As of late tonight, there were reports of no other arrests.

[Reuter said Salonga was shown an arrest warrantly by a colonel who came to his room in a Manila hospital where he is being treated for asthma. Salonga said the colonel "just showed it to me' and then took it back, saying he did not want to worsen Salonga's condition by actually serving it. Salonga told The Associated Press earlier that he had had no involvement in the bombings.]

Meanwhile, the Philippine government has made no new moves to present evidence to support a request that U.S. authorities investigate those on the arrest list known to be living in the United States.

At least 22 of the 30 cited are known to be out of the country, many of them in the United States. The most prominent are Benigno Aquino Jr., Marcos longtime foe, and Raul Manglapus head of the U.S.-based Movement for a Free Philippines. Some of the 22 have been gone for several years.

Authorities here claim the bombings were directed from the United States and implied that some of the bombs were smuggled from the United States.

Several weeks ago, the Philippines asked U.S. authorities to assist in apprehending anyone involved in the bombings. The State Department said it would investigate if any evidence is submitted but U.S. Embassy officials said today no evidence had been submitted to back up that request.

Marcos tonight sought to justify the arrest orders, saying they had been based on his personal questioning of Victor Burns Lovely, a Philippine-born American businessman who was seriously injured recently while allegedly working on a bomb in his hotel room here.

Marcos told reporters that Lovely "confirmed the existence of a conspiracy to destabilize the government through terrorism" that would include bombings and plots to assassinate public figures, including Marcos.

An organization known as the April 6 Liberation Movement has claimed responsibility for several of the bombings and has threatened more serious actions unless Marcos lifts martial law, which has been in effect eight years. a

No evidence has been made public in the Sunday bombing, which injured 18 persons, but Marcos yesterday ordered the arrest of the 30 persons, among them a half-dozen of his long-time critics here and in the United States.

Roxas and Laurel, two leaders of the opposition, were especially critical at a news conference today of the inclusion in the arrest orders of Salonga, a former senator who is also active in the new alliance.

"I personally feel Mr. Marcos has made a mistake," said Roxes. "I don't think Salonga could be in any way involved in the bombings."

Roxas said he thought Marcos acted hastily out of embarrassment over the bomb planted in his presence despite heavy security at the convention center and the large retinue of guards that always accompanies him in public.

All three of the major opposition leaders have publicly deplored the bombings, but said they show that many Filipinos feel there is no other effective way to confront Marcos and end marital law.

Roxas said today, "The people behind these bombings only want the restoration of civil and political rights."

When questioned about that statement, however, he backtracked, saying that he knew nothing of the people responsible for the bombings and did not know where they fit in the political spectrum.