Fancy-dress 'bomb' backfires on wearer

A man's fancy-dress choice could cost him thousands of dollars after he sparked a bomb scare that shut down part of central Christchurch.

The 29-year-old man dressed up as a suicide bomber for a "bad taste" costume party and discarded part of his costume - fake explosives - in a central city rubbish bin so he could get into bars.

The discarded item, made to resemble sticks of gelignite with wires and a clock, was found by a homeless man on Saturday and mistaken for a real bomb.

Police cordoned off three blocks of the city for several hours and called in Army explosive experts to destroy the device, causing hotels to be evacuated and local businesses to shut their doors for the day.

At least one hotel is now considering suing the man for up to $10,000.

Police considered charging the man, but found there was no criminal offence for him to answer.

"It was a man putting rubbish into a rubbish bin," said Detective Senior Sergeant Dave Harvey. The man was embarrassed and apologetic.

The plush Grand Chancellor Hotel evacuated staff and guests for about six hours. General manager Tim Stonhill said a lawsuit to recoup costs from the man was being considered.

"I fully understand that his actions were innocent, but nonetheless they did have consequences and they were his actions," Mr Stonhill said.

"I suppose it comes down to, in terms of law, what success would we have in making a claim, and I don't want to prejudge that. You could take the view that his actions were ... negligent."

Mr Stonhill said he had calculated the expense of the bomb scare at between $5000 and $10,000.

"The prime amount is staffing costs, because the staff were evacuated from the hotel for about six hours, so they then had to come back and carry on and do what they should have finished doing by then.

"So there were additional labour costs and other staff that had to get involved to help out and bring the hotel back to normal operation."

One guest missed an international flight because he could not get his passport from his room.

Canterbury Mags owner Grant Laffey said he would have lost up to $1200 in income by closing his store during the bomb scare, but legal action was not an option for him.

"It's not worth the effort. I'm just a small business."

Convenience store owner Sears Ha, who estimates he lost $2000, said he was upset to hear the man was not going to be charged.