The new-look square was officially opened this week, with new trees, plants, paths and seating. The Brassfounders column, dating from 1886, which sits in the square, has also been refurbished during the overhaul, which is part of a £1.5m refurbishment of the Old Town and Southside. Businesses in the square say they are delighted with its new look, but they and their customers are now being plagued by drinkers who spend the afternoons on the park benches, becoming loud and sometimes aggressive.

Mahmood Bashir, 39, of Mint Centre mobile phone shop, said: "They've done a good job, they've spent a lot of money and it does look nice, but they really need to police this area with the drunks.

"The guys keeps themselves to themselves, but sometimes they have a fight, then they have a shouting match. The public get upset because they're not used to hearing the foul language, and they get a wee bit scared when they hear the shouting matches.

"It does affect trade, because people don't like to hang around this area. It's an international area with lots of students and people move on pretty quickly."

Iftikhar Ahmed, 54, of Bismillah Food Store, added: "There's a big problem with them. They come all the time into the shop, sometimes not paying and there are sometimes problems with the customers. We've had to call the police many times. Ordinary people don't use the park because of it. We don't like this kind of behaviour."

Charles Nowosielski, of Through the Looking Glass Bookstore, was more philosophical about the situation: "It's taken a long, long time to do the square but I think once it settles down it'll be a good thing.

"We do miss the cherry trees, there are just three now. The guys do come in for a drink but as long as they don't get too noisy it doesn't matter."

Nearby Hunter Square is already a "designated enforcement zone", where outdoor drinking is outlawed, but Councillor Paul Edie, convener for housing and regeneration, said he thought existing powers were sufficient to control the problem in Nicolson Square.

He said: "We have a city-wide bylaw which says if you're drinking outside and not causing any hassle we'll leave you alone, but if you're causing trouble the police have quite wide-ranging powers, so there should not be any problem."

He added: "The place is looking fantastic. I've gone past this place several times over the years and it was always open but it never looked open. With all the work it's more open and inviting for people, it's a good community focal point and it's great to see people out there picnicking."

A police spokeswoman said local officers had worked at reducing antisocial behaviour in and around Nicolson Square in recent months, and with some success.

She added: "We're not looking at bringing in the same measures as at Hunter Square."