Boston: A Boston police captain's son has been arrested for building bombs in his apartment and planning to attack a crowded university campus cafeteria on behalf of the Islamic State militant group, authorities said.

Alexander Ciccolo, 23, was arrested on July 4 for the unlawful receipt of multiple guns, the US Justice Department said in a news release. His indictment was unsealed on Monday. The university he intended to target was not disclosed.

In this July 26, 2012 picture Alexander Ciccolo participates in a peace walk through Brighton, Ontario, Canada. Credit:Dave Fraser/AP

Mr Ciccolo has received mental health treatment since childhood, according to sources familiar with the family. His father recently alerted authorities to his concerns about his son's activities, the sources said.

FBI agents put Mr Ciccolo under surveillance after being alerted to some of his posts on social media. They watched him buy at least one pressure cooker at a Wal-Mart store in Massachusetts, according to an affidavit by FBI special agent Paul Ambrogio.