Arati Jerath, the political editor of Indian newspaper Daily News and Analysis, told Al Jazeera she thought the police suspected a "Bangladesh militant group which we call Huji".
"The police here suspect that it [Huji] is based in Bangladesh but they have local modules - sleeper modules - all over, particularly in South India and the state of Maharashtra. These are disaffected youth or fanatical groups."
Asked if these groups had been behind earlier attacks, including the bombing of a mosque in Hyderabad in May, she said: "There is a suspicion that it is the same network that was involved.
"I think police have found some connections between these because they've traced some of the chemicals used in the bombs to a lab in Nagpur in the state of Maharashtra. The same lab had supplied chemicals used in some of the other attacks."
Five explosive devices detonated and at least 19 other bombs were found and defused in Hyderabad, police said.
No one has claimed responsibility for the blasts but Sriprakash Jaiswal, India's interior minister, said they were part of an effort to undermine the city's mixed Hindu-Muslim community.
"One terrorist group or the other, which is bent on destroying the unity of the country, is certainly involved," he said.
About 40 per cent of the city's seven million people are Muslim.
Hyderabad's city administrator said late on Saturday that police had some leads.
Officials have previously linked Harkat-ul-Jehad-i-Islami to the bombing of a 17th-century mosque in Hyderabad in May that killed 11 people.
|"We're seeing a pattern of attacks every two to three months somewhere or other in the country on soft targets" |
head of the
New Delhi-based Institute for Conflict Management
But police have never named any suspects in the attack and little evidence linking the group to the blasts has been made public.
Some Muslims have said that Hindu extremists were to blame for the mosque bombing.
After the attack, five people were killed in clashes between security forces and Muslim protesters angered by what they said was a lack of police protection.
India has suffered a series of recent attacks including seven bombings on Mumbai's rail network which killed 186 people in July 2006.
Authorities have blamed them on groups seeking to upset a peace process between India and Pakistan and stir Hindu-Muslim violence.
Much of India's violence is rooted in disputes over the Himalayan territory of Kashmir, which is divided between India and predominantly Muslim Pakistan but claimed in its entirety by both countries.
"We're seeing a pattern of attacks every two to three months somewhere or other in the country on soft targets," Ajai Sahni, head of the New Delhi-based Institute for Conflict Management, said.
The explosion at the Lumbini amusement park took place during a laser show, about 500 people were in the park's auditorium at the time.