A full-page newspaper advertisement printed Wednesday is asking the Nova Scotia Heritage Trust and other groups to stop the "obstruction" of the new Halifax convention centre and leave economic development "to those who step up to advance our city."

"It's time to be bold," the ad reads, borrowing the new slogan for the city of Halifax. The city is at a critical economic juncture and cannot afford to stall momentum, the ad says.

"Continued obstruction of the new Halifax Convention Centre and other development projects is not in the best interests of the citizens of Halifax and the province of Nova Scotia," the advertisement reads.

"Groups like the Heritage Trust must focus on their own mandate and leave the business of economic development to those who step up to advance our city."

It's signed by more than 300 companies and business people. The Heritage Trust has argued the design of the convention centre is too big for the downtown and has gone to court asking that the project be quashed.

Brent Ronayne, a realtor with Red Door Realty, put his name to the message. He said barriers to development discourage investment in the city.

"I think it's time we step up and, as the ad says, be bold," he told CBC News.

"A lot of people may feel the trust is stepping out of its mandate. They want to promote public interest in conservation, historic structures. In this case, there is really no historic asset that is being affected."

Ronayne sits on Halifax's Heritage Advisory Committee, too, and believes the city's visible history is an important part of its appeal.

'Halifax is open for business'

"But as a Realtor, as a professional under 30, I know people have left because they felt the economic situation just wasn't there," he said.

The heritage preservation must balance against economic growth, he argued.

Andre Levingston owns the Halifax Rainmen, who play downtown in the Metro Centre. He put his name behind the ad.

Andre Levingston wants a thriving downtown. He says good development is crucial for that. (CBC)

"We should send a message that Halifax is open for business. I think being a little bit aggressive, sending a bold statement that we want to see a bit more changes here, is very important for people to put out there," he said.

It's not about discouraging discussion, he said, but about building the downtown core to attract people and commerce.

"We want to make sure we do some things to keep our young people here," he said. Levingston added that includes economic development that creates jobs.

"I'm excited for the development that's happening in Halifax. We'd like to see a thriving downtown."

Last month, convention centre developer Joe Ramia filed a lawsuit against the Nova Scotia Heritage Trust and its board of directors, saying the opposition is costing him money.

At that time, board member Phil Pacey called the lawsuit personal and upsetting.

Linda Forbes, the president of the Nova Scotia Heritage Trust, said Wednesday she is surprised by the advertisement but feels it is within her group's mandate to push the city to follow its own rules. She said the trust has no issue with any developer and its issue is with the city.