Buddhists are rarely targeted in India but there have been tensions in the wider region recently following clashes between Buddhists and Muslims in Myanmar, Sri Lanka and Bangladesh.
In neighbouring Nepal, dozens of police have been mobilised to guard the country's famed Buddhist temple complex as a precaution after the India attacks.
Police have doubled to 70 the number of security officers guarding the Lumbini temple complex, 250 kilometres (150 miles) southwest of the capital Kathmandu, local police official Surendra Bahadur Shah told AFP.
Thousands of pilgrims visit Lumbini each year to pay homage to the Buddha, who is said to have been born in the temple gardens in 623 BC.
Ten small devices exploded on July 7 in the Bodh Gaya temple complex in the eastern state of Bihar, wounding two monks, while three others were defused at the historic shrine.
The National Investigation Agency released two sketches of a man suspected of planting the bombs at the complex, a UNESCO World Heritage