BANGKOK — Thai authorities said on Wednesday that the group of Iranians detained after an explosion tore the roof off their rented house was on a mission here targeting Israeli diplomats.

Thai police released images of three men who were suspected to have been involved in bomb explosions in Bangkok.

“This much I can tell you — the target of the operation was specifically the Israeli diplomatic staff,” Gen. Prewpan Dhamapong, Thailand’s chief of police, said in a television interview.

Two Iranian suspects remained in custody in Bangkok on Wednesday, including one man who lost both legs after detonating a bomb when confronted by police on Tuesday. A third Iranian suspect who fled to Kuala Lumpur, the Malaysian capital, was arrested on Wednesday by Malaysian police, who said they were holding him on the request of the Thai authorities. A fourth suspect, a female, left the country on Feb. 5, police said.

Explosive devices discovered by police in the group’s rented house were similar to those used earlier this week against Israeli diplomats in India and Georgia, according to Mr. Prewpan and Israel’s ambassador to Thailand.

“It’s almost the same system that was used in Delhi and in Tblisi, which leads us to think that they are connected,” Itzhak Shoham, Israel’s ambassador to Thailand, said in a telephone interview.

Iranian officials immediately rejected the accusation. An Iranian Foreign Ministry spokesman, Ramin Mehmanparast, called the accusation of Iran’s involvement “baseless” and accused Israel of trying to damage its relations with Thailand, The Associated Press reported.

The Israeli authorities said the discovery of explosives in Bangkok fits a pattern of Iranian-backed attacks on Israeli targets.

Mr. Shoham said he believed Bangkok had been chosen because it was a “soft target.”

“It’s easy to come in and out, to rent a house,” he said. “Nobody pays attention to people coming and going.”

Mr. Shoham said the devices seized in Bangkok contained the same type of explosive as those in New Delhi and Tblisi, the Georgian capital, and were similarly outfitted with magnets that would allow them to be attached to metal objects. The bomb used in the New Delhi attack and the device discovered on the car of an Israeli Embassy staff member in Tbilisi were attached to vehicles using magnets.

Some Thai officials said Wednesday it was too early to confirm links between the Bangkok explosions and the incidents in India and Georgia. But Mr. Prewpan, the police chief, said the devices found in Bangkok were the “same” as those in India and Georgia.

Mr. Prewpan spoke after interrogating one of the suspects who was detained on Tuesday at Bangkok’s international airport as he tried to leave the country. The man had shrapnel wounds from the explosion in the house, Mr. Prewpan said.

Thai officials were on the defensive as they described investigations into the three explosions on Tuesday in a residential neighborhood of Bangkok. They were only tipped off to the Iranian group’s activities after what appeared to be an accident: The first blast on Tuesday destroyed the roof of the group’s house and forced the Iranian suspects to flee. The second and third explosions came soon after, when witnesses saw one of the Iranian suspects throw a bomb at a taxi while he was fleeing; minutes later, he detonated another device as he was confronted by police, severing one of his own legs and badly injuring another.

Wichean Potephosree, the head of Thailand’s national security council, described the country’s tourism industry as a “weakness.” Last year Thailand, one of the most popular tourist destinations in Asia, welcomed 17 million foreigners.

Chalerm Ubamrung, Thailand’s deputy prime minister, said the government would tighten immigration procedures.

“I will order the Immigration Bureau to closely monitor people who enter the country, especially from countries that might have some troubles,” Mr. Chalerm said. He did not define “troubles.”

The tourism ministry announced Wednesday that it would suspend the practice of issuing visas on arrival to Iranian citizens.

Last year Thailand’s immigration office issued 148,235 tourist visas to Iranians.