Jones and the band left the stage, and an official subsequently announced the gig would have to be abandoned, reported BBC.
Neil Winterbottom, director of the company behind the concert, Loose Cannon Events, apologised in a statement.
"Unfortunately, during Sir Tom Jones' performance... There was an issue with the generator power supply which meant that the concert finished abruptly.
"I wish to make it clear that this situation is not associated with the artist or his management team or Alnwick Castle... We are investigating the incident. We are sorry to disappoint concert-goers with the abrupt end to the concert," it read.
