Israel blamed Iran for twin attacks Monday targeting Israeli embassy personnel in New Delhi and Tbilisi, Georgia, as well as blasts in Bangkok a day later. Iran has denied the charges.
Indian investigators did not rule "local help" in the New Delhi attack, in which the wife of an Israeli diplomat and three others were wounded, the Times of India reported.
Investigators suspect a motorcyclist who had been following the embassy vehicle stuck a magnetic explosive device in the back of the vehicle before speeding away as the device was set off by remote control. In the similar attack in Tbilisi, the device was discovered by the vehicle's driver and later defused.
The Times said the device used in the New Delhi attack was highly sophisticated and had not been used in India before.
Home Minister Palaniappan Chidambaram condemned the attack, saying diplomats of every country are entitled to live and work in India in peace and security.
"It is quite clear that a very well-trained person has committed this attack," he said. "There is reason to believe that the target was the Israeli diplomat's wife and, therefore, one has to proceed on the basis that it was a terrorist attack."
He said it appeared the attacker attached the device on the back of the embassy vehicle as it waited at a traffic signal and then sped away.
"We condemn the incident and, at the moment, I am not pointing a finger at any particular group or any particular organization but whoever did it, we condemn it in the strongest terms," Chidambaram said.
He said Indian officials have assured Israel the investigation will continue until the attackers are found.
In her daily media briefing in Washington Tuesday, State Department spokeswoman Victoria Nuland condemned the attacks, including the ones in Thailand, adding the U.S. is awaiting results of the investigations.
However, she said, the latest events come on the heels of other disrupted attacks targeted at Israel and Western interests, including an Iranian-sponsored attack in Baku, Azerbaijan, and an earlier Hezbollah-linked attack in Bangkok.
"So they serve as a reminder that a variety of states and non-state actors continue to view international terrorism as a legitimate foreign policy tool, which we consider reprehensible," Nuland said.
When asked about Israel blaming Iran for the attacks, she said the United States is waiting for the results of the investigations.
"We have offered to assist in these investigations. However, we do note that they come on the heels of other disrupted attacks that do have Iranian fingerprints on them," she said.