TEHRAN, Young Journalists Club (YJC) - Two bank officials told Reuters the street outside the building near the World Trade Center in the capital, Colombo, was blocked to traffic before the security alert was lifted.
Underscoring the nervous atmosphere in the Indian Ocean nation, authorities also shut the entry road to Colombo's main airport after a suspicious vehicle was spotted at a car park.
The road was reopened when the alert was declared a false alarm.
A police spokesman also said there was an explosion in a town east of the capital but there were no casualties.
The cause was not clear but it was not a controlled detonation like other blasts in recent days and was being investigated, he said.
With fears of more bombers ready to strike, police said they had asked people to leave offices early in Colombo's business district to avoid throngs at rush hour.
City-center restaurants were also shutting early.
More people, including foreigners, were swept up for questioning overnight as domestic and international authorities investigated deeper into the bombings, believed to have been the deadliest such attack claimed by Islamic State.
About 500 people were also wounded in the attacks on three churches and four hotels.
Police said 16 people were detained for questioning overnight, taking the number held since Sunday to at least 76.
They include a Syrian national, detained after police got information about him from Sri Lankan suspects.
One of those detained overnight was linked to a terrorist organization, police said, but gave no details. Another was taken into custody after "hate speech" was discovered on their Facebook page.
"It was related to the spreading and preaching of terrorism," a police spokesman said.
Police later arrested three people and seized 21 locally made grenades and six swords during a raid in Colombo, a spokesman said. He did not give details or suggest that the raid was linked to the suicide bombings.
An Egyptian and several Pakistanis have also been detained in the broader crackdown but there was no suggestion they had any direct links to the attacks.
Source: Reuters