Jakarta – A small pipe bomb exploded near the main United Nations building in Indonesia's capital yesterday, just a day after the trial of the leader of a radical Islamic group opened here.

No injuries were reported from the pre-dawn blast, which slightly damaged a foot bridge spanning a major downtown avenue and left a 30-cm hole in the pavement. The explosion was about 30 m from the UN building, which was not damaged, a UN security official said.

A search of the surrounding area turned up two small unexploded devices, police said. "We don't even know if the device was aimed at our building," said the UN security official.

National police chief General Da'i Bachtiar maintained that the bomb was just a low explosive to trigger fear among the public. Speaking to journalists, he said the blast could also be aimed at showing that the group committing the bomb attacks continues to exist.

No one claimed responsibility for the explosion. People in Jakarta were shocked by the blast as it happened a day after Jemaah Islamiah (JI) leader Abu Bakar Bashir went on trial for a series of bombings which the prosecutors said were aimed at weakening the government.

Almost at the same time as the opening of Bashir's trial, police arrested 18 other JI members on charges of involvement in terrorism. The UN has blacklisted JI as a terrorist organisation.