A blast occurred at the Kamakhya railway station on the outskirts of the city on Friday morning barely hours before the inauguration of the 33rd National Games.
There were, however, no casualties, police said.
The blast occurred between the old and new buildings of the railway station, which did not disrupt movement of trains, they added.
The station was being used over the past few days to pick up a large number of sportspersons who had arrived in the city to participate in the games to avoid the rush at the Guwahati railway station, police said.
A senior police official had received a phone call on Wednesday from a person claiming to be ULFA commander-in-chief Paresh Barua, who said two programmable time devices had been planted on the railway track near the Kamakhya railway station.
The caller had also said ULFA should not be blamed for any blast as it had withdrawn the Games boycott call.
Following this, the six-km stretch along the railway tracks from Kamakhya station to Bharalumukh station, towards Guwahati, was dug up on Thursday night, but no bombs or explosives were found, police said.
UPA Chairperson Sonia Gandhi is scheduled to inaugurate the National Games.