Ottawa Mayor Jim Watson says it's back to the drawing board on a proposed modern addition to the historic Château Laurier hotel, and even the city councillor who favoured it at first is backtracking after a wave of angry public feedback on the designs.

The plan — proposed by Larco Investments, which two years ago bought the iconic building in downtown Ottawa just steps from Parliament Hill — would be to move its parking lot underground and add up to 200 rooms in an addition designed by Peter Clewes, one of the leading architects in Toronto's condo boom.

The City of Ottawa and the National Capital Commission would need to approve the plan before it could move ahead.

As the public outcry mounted Wednesday when pictures of the plan were released, Watson tweeted his displeasure with the proposal.

Asked Thursday to expand on his thoughts, Watson said he doesn't think the modern design of the addition blends well enough with the old hotel.

"Well I'm not all that impressed with [the design], to be perfectly honest. The Château Laurier is an iconic heritage property in the downtown core, and the images that I've seen really don't blend well, in my opinion. And I've heard an awful lot of feedback, most of it negative, from the public. My hope is that we reach some compromise, as we always try to, between the developer, the NCC, the city and the public," he said.

"We have to approve, obviously, the plans, as does the NCC, and I sit on the board of the NCC now. It's important that these kinds of developments blend in and are compatible ... and I don't believe the images that I've seen create that kind of blending between old and new."

Chateau Laurier Ottawa hotel expansion

Here's another view of the proposed expansion from the Rideau Canal, itself a UNESCO world heritage site. (Supplied)

Councillor backtracks

Coun. Mathieu Fleury, who represents the Rideau-Vanier ward the hotel sits in, was quoted in the developer's promotional media release about the plan. He called it an "exciting project" and "captivating architectural design" that highlights the hotel's important heritage and location.

Mathieu Fleury Rideau Vanier Councillor

Rideau-Vanier Coun. Mathieu Fleury is apologizing for allowing himself to be quoted in a developer's promotional media release. (CBC)

But Fleury backtracked from that position somewhat as the negative feedback continued to pour in, saying the quote used in the developer's release didn't fully express his feelings, and that he was mainly pleased with the plan to demolish the existing five-storey parking garage.

He also apologized for allowing himself to be quoted in the promotional release in the first place, saying it was the first time he did it and that he won't do it again.

The iconic downtown building is owned by Larco Investments, but the hotel is managed and operated by Fairmont Hotels & Resorts.

The hotel said Thursday that Larco is reviewing the public feedback, and said it "appreciates the passion" people have for the Château Laurier.