Israel and the United States at the time warned their citizens to be alert in the capital, but Thai authorities said Thailand appeared to have been a staging ground but not the target of any attack.
Pansiri, the senior Thai police officer, said that "so far, we haven't found any links between these two cases."
Thailand has rarely been a target for international terrorists, but its main airport is a major hub for Asian air travel and its government — heavily reliant on tourism — is tolerant of foreigners and is often accused of corruption and graft.
Since 2004, it has faced domestic Muslim insurgency, but violence has traditionally been limited to the country's three southernmost provinces.
In New Delhi, Indian investigators were scanning closed-circuit TV video in their search for the motorcyclist who stuck the bomb to the Israeli Embassy car that injured four people, including a diplomat's wife. She was in critical but stable condition.
Indian Home Minister Palaniappan Chidambaram said it appeared to be a terrorist attack carried out by a "very well-trained person."
Israeli media reported that Mossad teams are in Bangkok and New Delhi to investigate the explosions.
Associated Press writers Jocelyn Gecker in Bangkok, Bradley Klapper in Washington, Ravi Nessman in New Delhi, and Amy Teibel and Ian Deitch in Jerusalem contributed to this report.
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