More than 100 small bombs that shook Bangladesh Wednesday, the near-simultaneous attacks killing two people, injuring at least 125 and sparking widespread panic.
Police arrested about 50 people in connection with the bombings, which affected nearly every big town across the country, the state-run news agency, Bangladesh Sangbad Sangstha, reported.
The police are now on the look out for a man known as Bangla Bhai who trained in Afghanistan and lived in madrassas in Karachi as the possible mastermind behind the attacks, NDTV says.
Leaflets calling for the imposition of Islamic Law by the banned group the Jumatul Mujahedin were found at a number of explosion sites.
This February, the Bangladesh government had outlawed the group along with the Jagrata Muslim Janata for alleged killings, robberies and bomb attacks. The two groups are suspected to be working in coordination with each other.
The Bangladesh Nationalist Party led by Khaleeda Zia has long resisted attempts to rein in Islamist hardliners who have enforced hijab and namaz forcefully in areas bordering India
Khaleda Zia, the prime minister, who had left for China before the blasts, said the attackers wanted to create panic and instability, and she called the events a "cowardly, conspiratorial and well-planned terrorist act", according to AP.
The UN secretary-general, Kofi Annan, condemned the "senseless acts of indiscriminate violence".
Many of the homemade bombs were packed just with sawdust, rigged with battery-powered timers and planted outside government offices or courthouses. Some were left at press clubs, bus and train stations, and markets.
In Dhaka, about a dozen bombs exploded near the airport, at court buildings and in markets, said a city official, Kalpana Rani Dutta.
An anti-government strike for Saturday was demanded by the main opposition, whose leader, Sheikh Hasina, said the government's failure to stem crime had allowed the attacks to happen. In recent years several small militant groups advocating Islamic rule have sprung up in Bangladesh, mostly in the poorer regions.