The Crown Prosecution Service spent £20,000 on the trial of a man accused – and later acquitted – of stealing a 25p banana, it has emerged.

James Gallagher, 23, was found not guilty this week of stealing the fruit from an Italian restaurant in Birmingham's Bullring shopping centre before it opened at 8.45am on 13 March.

The two-day trial was heard in Birmingham crown court rather than a magistrates court – incurring significantly more costs for the CPS – because Gallagher elected to have his case heard in front of a jury. He said he believed that magistrates would have found him guilty.

Gallagher, from the Handsworth area of Birmingham, said after the trial: "It's shocking, it's just a waste of taxpayers' money. I cannot understand how they've got away with it."

The CPS defended its decision to spend around £20,000 on the case. In a statement, Martin Lindop, the district crown prosecutor for Birmingham, said: "It is not the cost of the item that determines whether we proceed with a prosecution, but whether there is sufficient evidence for a realistic prospect of conviction and it is in the public interest.

"In this case, we felt that there was sufficient evidence and it was in the public interest for the prosecution to proceed."

Niall Skinner, for the defence, told the jury that Gallagher and another man, who was given a 12-month conditional discharge after pleading guilty in March, were tipsy after drinking to celebrate Gallagher's 23rd birthday. He argued that Gallagher had not been given the chance to pay for the banana, even though the restaurant had not opened, because security guards had acted so quickly.