Israel accused Iran of waging a covert campaign of state terror that stretched this week from the Middle East to the heart of Asia after a bungled series of explosions led to the capture of two Iranian nationals in Bangkok.

Authorities in Israel ratcheted up security at home and abroad following Tuesday's explosions in the Thai capital, escalating a confrontation over Iran's suspect nuclear program and raising fears of war.

On Monday, an Israeli diplomat's wife and driver were wounded in New Delhi when a bomb stuck to their minivan exploded, and another device was defused on an Israeli Embassy car in Tbilisi, Georgia.

Israel has threatened military strikes on Iranian nuclear facilities, and Iran has blamed the Jewish state for the recent killings of Iranian atomic scientists.

Iran denied responsibility for the New Delhi and Georgia attacks, which appeared to mirror the killings of the Iranian scientists that used "sticky bombs."

Four Thai civilians wounded

The series of blasts in Bangkok wounded four Thai civilians and blew off the leg of an Iranian who had fled a house carrying what looked like grenades after a cache of explosives ignited there, apparently by mistake.

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Wreckage of a taxi lies at the scene of an explosion in Bangkok. It's not immediately clear whether any of Tuesday's attacks were linked to bombings in India and Georgia. (Apichart Weerawong/Assoaciated Press)

When police searched the Iranians' home, the bomb squad found and defused two explosives, each made of three or four pounds of C-4 explosives inside a pair of radios, and National Police Chief Gen. Prewpan Damapong said the bombs were "magnetic" and could be stuck on vehicles.

The wounded Iranian was in police custody at a Bangkok hospital and immigration police detained a second Iranian as he tried to board a flight for Malaysia. Security forces hunted for a third Iranian suspect.

Israel's Channel 10 TV quoted unidentified Thai authorities as saying the captured Iranians confessed to targeting Israeli interests. The site of the blast is just a few kilometres from the Israeli Embassy.

There was no comment from Iranian officials in Tehran on Tuesday's series of explosions in Thailand.

Thai government spokeswoman Thitima Chaisaeng said "we need more analysis" to determine who was behind the attack and whether Iran was involved. She refused to comment on what the Iranians might have been planning or whether targets had been identified.

There seemed to be no doubt in the minds of Israeli officials, who blamed Iran and its Lebanese ally, Hezbollah.

"The attempted terrorist attack in Bangkok proves once again that Iran and its proxies continue to perpetrate terror," Defense Minister Ehud Barak said in Singapore. "The recent terror attacks are yet another example of this."

Iran and Hezbollah are "unrelenting terror elements endangering the stability of the region and endangering the stability of the world," added Barak, who was in Bangkok on Sunday, according to Israel's Defense Ministry.

Added Israeli Public Security Minister Yitzhak Aharonovitch, in an interview with Israel Radio: "We know who carried out the terror attacks, we know who sent them, and Israel will settle the score with them."

Thwarted attacks

On Monday, Prime Minister Benjamin Netanyahu said Israel had thwarted attacks in recent months in Azerbaijan, Thailand and unspecified other countries.

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Indian investigators were searching Tuesday for the motorcycle assailant who attached a bomb to an Israeli diplomatic car in the heart of New Delhi. (Mustafa Quraishi/Associated Press)

In Israel, police spokesman Micky Rosenfeld said security was heightened at public places, foreign embassies and offices, as well as Ben-Gurion International Airport. He said patrols have been stepped up and police were instructed to be especially vigilant.

The first blast in Bangkok ripped off part of the roof of an explosives-filled house where the three Iranians were staying, police said.

Surveillance video from just after that blast showed separate images of each of the three suspects walking down the middle of a residential street.

One man -- identified by police as Saeid Moradi -- could be seen wearing a baseball cap and a dark jacket. He carried a large backpack over one shoulder and what appeared to be two portable transistor radios -- one in each hand.

"He tried to wave down a taxi ... and the driver refused to take him," Police Gen. Pansiri Prapawat said. Moradi responded by hurling an explosive device -- possibly a grenade -- that partially destroyed the taxi and wounded its driver.

Police then tried to apprehend Moradi on a nearby street. He hurled a grenade at them, "but somehow it bounced back" and blew off his leg, Pansiri said.

'We know who carried out the terror attacks, we know who sent them, and Israel will settle the score with them' —Israeli Public Security Minister Yitzhak Aharonovitch

Photos of Moradi showed him lying on a sidewalk strewn with broken glass in front of a primary and secondary school. Hospital officials said his right leg was sheared off below the knee, while his left leg was severely mangled.

Police said a second Iranian, Mohummad Hazaei, was detained at Bangkok's international airport; he had been seen in the closed-circuit TV video also carrying a large backpack. He wore sunglasses, a T-shirt, pants and tennis shoes.

The third Iranian, dressed in camouflage shorts, carried nothing.

Three Thai men and one Thai woman were wounded and treated at a hospital, said Dr. Suwinai Busarakamwong.

Authorities are trying to trace Moradi's movements. Initial reports indicated he arrived in Thailand from Seoul, South Korea on Feb. 8, Pansiri said, landing at the southern resort of Phuket, and staying several nights in a hotel in Chonburi, a couple hours drive southeast of Bangkok.

A bomb disposal unit checked a dark backpack near the spot where Moradi fell and police found Iranian currency, U.S. dollars and Thai money, Pansiri said.

Prime Minister Yingluck Shinawatra called on people "not to panic" and said the situation was under control..