Most schools in the quake-devastated Canterbury region are not likely to open until Monday, says Education Minister Anne Tolley.

"So far today the Ministry of Education has contacted 100 of the 165 state and state-integrated schools in the affected areas," Mrs Tolley said this afternoon.

"No school has said it intends opening for students tomorrow, though many are likely to open for teachers and staff."

However, she said Civil Defence had the legal right to close schools and had indicated some may open to students tomorrow.

Mrs Tolley said parents could contact schools or visit the Ministry of Education's website for updates on which schools were planning to open.

"We want to get schools and early childhood education services open as soon as possible, and the ministry has a management plan in place to do this, but our main consideration must be the safety of students and staff."

Earthquake bill may top $4 billion

Meanwhile final bill for the Christchurch earthquake may reach $4 billion, almost double initial estimates, Treasury Secretary John Whitehead said this afternoon.

Dr Whitehead said Treasury was working on the assumption the Earthquake Commission was likely to pay out $2 billion in claims resulting from the earthquake but the wider bill would be far higher.

"If you take the effect on others beyond that you're probably talking about something in order of doubling that," Dr Whitehead said.

"The costs faced by the EQC, by individuals, by businesses, by insurance companies will probably be in the order of $4 billion."

Dr Whitehead said there were chances the actual bill would come in higher or lower.

One factor that might see it increase was whether homes could be rebuilt on the same land.

"Until geologists and others do their work we don't really know."

Treasury has a four-person team working on earthquake-related matters which reports to the taskforce from the Department of the Prime Minister and Cabinet, which is coordinating the overall Government response to the earthquake.

Wage subsidy applications open tomorrow

The Government's emergency wage subsidy scheme for workers who aren't being paid because of the Canterbury earthquake will be open for applications from tomorrow.

The Government yesterday announced the scheme, which will provide a $350 a week subsidy to employers so they can continue to pay workers.

The subsidy is for businesses with fewer than 20 employees which can't trade or pay their workers because of earthquake damage.

It will initially last for four weeks and businesses can re-apply after that.

Prime Minister John Key said up to 5000 businesses could fit into the category and up to 77,000 employees could be eligible for the subsidy.

Businesses with more than 20 employees haven't been entirely ruled out and Mr Key said the scheme was flexible.

Mr English said today $15 million had been put aside for the subsidy.

He said affected businesses could apply to Work and Income for the subsidy from tomorrow and would be paid within 24 hours.

Payments would be backdated and employers could top the payments up if they were able.

"The Government has deliberately fast-tracked this response because we are aware that small businesses who for instance turned up to work on Monday and had nothing to sell could find themselves very rapidly under financial pressure and unable to pay their staff..." Mr English said.

Map: Christchurch earthquake damage
Red marker: Epicentre
Blue markers: General damage
Green markers: Public service advice and information
Yellow markers: Locations of welfare centres
Purple markers: Damage to historic buildings
Pink markers: Buildings set for demolition

View Christchurch earthquake in a larger map

- NZPA, NZ Herald staff