The cost of building Christchurch's 30,000-seat multi-use arena has jumped significantly with the contractor reporting it could increase by up to $150 million.

The final design and construct submission from lead contractor BESIX Watpac has been received. That, along with projected volatility in the commodity market, has increased the expected price to $683 million.

The opening date is also expected to be delayed once again, until April 2026.

BESIX Watpac has been asked to bring the costs down and to provide a fixed price over the next week to eliminate the risk of more cost escalations to the Christchurch City Council,

"We are very concerned that the overheated construction market has driven this project so far over budget," Te Kaha Project Delivery Limited chairman Barry Bragg said.

The risk of the build cost for the area rising from the budgeted $533m had already been signalled, given the impacts of the pandemic and the war in Ukraine on the global commodity market and supply chains.

"However, we did not expect the cost to escalate to this level."

Council chief executive Dawn Baxendale said the significantly increased costs

She said if Te Kaha Project Delivery Limited cannot bring the project more in line with the budget, the council will need to decide whether it wants to increase the budget, scale back the project or halt it.

"The council is going to have to make some very difficult choices because it is clear that building the city a multi-use arena will be far more expensive than envisaged," she said.

"Clearly the council is disappointed to hear that figure and we absolutely will be wanting to consult the public on how they feel about where we currently are."

The council may choose to complete the detailed design and then reprice the project in the market when prices may have come down, Baxendale said.

The option of scaling back the project would increase the timeline further as it would mean starting back at the concept design phase, Bragg said.

An early estimate provided to the project board shows in order to stay within the $533m budget, the stadium would need to be reduced to 20,000 seats - 17,000 permanent and 3000 temporary.

Choosing this option would also delay the project into 2027, Bragg said.

Crusaders CEO Colin Mansbridge said he was not surprised by the news.

"Every project going on at the moment, there is lumpy cost escalation but the consequence of it is gutting.

"It feels like Groundhog Day more than anything else. It feels like a gut punch. I don't blame council for stopping and taking a breath, but it feels like we're never going to get there and that's what worries me a little bit. I don't feel whole or the city feels whole." he said.

Mansbridge said the prospect of halting the project is "ridiculous."

"Christchurch is the biggest city in the South Island, second largest in the country. We grow people and they achieve amazing things all over the world.

"It would be ridiculous not having a 'whole city'. I can't imagine it."

He said the Crusaders would like to see the council continue with the project.

"There's some risk to that, but if we don't we'll be sitting here in five years with a smaller venue costing the same amount and really frustrated with how we got to that point. Sooner or later we've got to get on with it, I think."

A report recommending the council begin consulting the public on the options will be presented at a council meeting on June 9. If approved, consultation will start on June 10.

The project was marred by controversy last year when the city council decided to slash seating capacity to 25,000, after saying the budget had already blown out by $131 million.

The decision divided the city, with thousands signing an online petition to stick with the original capacity, fearing they could miss out on big All Blacks matches and other key events and prompted a U-turn to the original 30,000 capacity.

Work on the multi-use arena (CMUA) was initially due to be completed by the end of 2024 but the increase in seats pushed it out to mid-2025.

Earlier this month the Herald reported the project had been delayed a further six months until the end of 2025.