Kathmandu  - A bomb explosion in central Kathmandu injured one person, police said Thursday.

The blast targeted a busy public transport station in the commercial district of the Nepalese capital.

Police said one person sustained injuries when the bomb, left near a letter box outside the general post office, exploded and ripped through a crowded commercial area.

The area was packed with people waiting for public transport. Police said they were surprised there were not more casualties given the intensity of the blast.

The bomb was an Improvised Explosive Device (IED) made from iron pipes, police said.

There were no immediate claims of responsibility. However, police say they suspect insurgent groups based in southern Nepal to be behind the latest attack.

Police sealed off the area and additional reinforcements and bomb disposal units searched for more bombs. There had been no arrests Thursday.

On Sunday, annother home-made bomb went off near Nepal's only international airport, also injuring one.

A group calling itself Ranavir Sena claimed responsibility for the blast. The group is demanding annulment of the government's decision to declare Nepal a secular state and wants Hinduism reinstated as the state religion.

Nepal was declared a secular state in 2006 after a mass movement toppled former king Gyanendra's government and brought the country's Maoist rebels into mainstream politics.

The increase in attacks in Kathmandu also coincides with the government's efforts to bring armed rebel groups in southern Nepal in for formal negotiations to end violence.

There are dozens of armed groups operating in the southern Nepalese plains and eastern hill districts. Their demands range from a separate state for predominant ethnic groups to reinstatement of Hinduism as the official region. (dpa)