Before the state election in 2014, the Labor party vowed to establish a $100 million fund to ensure that all Victorian government schools would be "asbestos free" by 2020.

It came after Fairfax Media revealed a secret state government audit found some schools were so plagued with the toxic material that the buildings needed to be cordoned off immediately.

But under questioning by the Shadow Minister for Finance, David Morris, at the State Parliament's Public Accounts and Estimates Committee on Tuesday, Mr Merlino said a suggestion that the government promised to remove asbestos from every single school was "farcical".

The cost of ridding all schools of the toxic material would have cost the state more than $1 billion, Mr Merlino said. The government would target asbestos that posed a medium and high risk to students and staff.

"We are not going to be removing 30,000 buildings to address asbestos that may be in the foundations, or that may be in the roof cavity," the Minister said.

"The commitment was a state-wide audit and removal of asbestos that posed an immediate risk to students ??? we are delivering our election commitment in full."

The Opposition has seized on Mr Merlino's comments, with Opposition Education spokesman Nick Wakeling accusing the government of "walking away" from an election promise.

"Before the election they promised to remove every inch of asbestos by 2020 and today the minister concerned and his government will break yet another election commitment," Mr Wakeling said.

"When they were in Opposition, this government prided themselves under a banner of 'no more asbestos in Victoria schools under Labor', and this has been proven to be yet another lie."

Victorian Greens education spokesperson Sue Pennicuik said "the government should be sticking to their promise".

"There is no safe exposure to asbestos, it is extremely dangerous substance and it shouldn't be in schools."

The budget for asbestos removal has already blown out to $155 million, with the government setting aside $85 million for the program in this year's budget.

The Victorian School Building Authority estimates that up to $270 million would still be needed.

Since taking office, the government has conducted a statewide audit of 1712 government school sites and found high risk asbestos at 497 schools, which it removed by March last year.

Over the next three years, it will replace 100 school buildings with new classrooms and remove asbestos at more than 1200 schools, Mr Merlino said.

"When we came to office, one in three schools contained high-risk asbestos. Within 18 months we had removed it all."

President of the Australian Education Union Victorian Branch Meredith Peace "commended" the government for "the work completed so far" on asbestos removal.

David Martin, who is the information officer at support and referral service Asbestos Wise, said removing asbestos from all school buildings was a "worthy idea", but it was bound to be "horrifically expensive" and was not necessary to protect students and staff.

Asbestos was safe if it was concealed and undisturbed, he said.

"It wouldn't be a problem unless someone kicks a football into it, cracking open the area. Then it goes from being safe to hazardous."