Extensive damage from the Christchurch earthquake may cause the demolition of city's town hall and convention centre, which were today closed until at least the end of 2012.

Venue managers Vbase today issued estimates on how long it will take to repair Christchurch facilities damaged by the February 22 quake.

It said the Christchurch Town Hall had suffered significant damage from liquefaction and ground displacement - the extent of which will not be known until the end of August.

Assessments of the damage to the Christchurch Convention Centre had been delayed for six weeks while the building was made safe, but it too had suffered substantial damage, the statement said.

Both buildings would remain closed until the end of 2012 at the earliest.

Vbase CEO Bryan Pearson said at this stage engineers were working on the assumption the centres could be repaired eventually.

But he said it was possible they would still find damage that cause the buildings to be demolished.

"We can't rule out the prospect we'll uncover damage that means the buildings will not be able to be repaired."

Meanwhile, AMI stadium was expected to reopen in February 2012 - in time for the next Super 15 season.

A contract to fix the stadium's Deans Stand would be awarded in early June, while work on rebuilding the playing surface was expected to be completed by the end of the year.