Questions must be answered over "disastrous" private finance initiative (PFI) deals for schools, First Minister Nicola Sturgeon has said.

The deals involved local authorities spreading the payments to private-sector contractors over decades at an additional cost.

Nicola Sturgeon told Holyrood during First Minister's Questions: "Questions must be asked, and in due course answered, about old PFI contracts that many at the time feared put profits before quality.

"The cost of Labour's disastrous PFI deals are still today taking significant sums of money away from vital public services."

SNP MSP Kenneth Gibson said his constituency of North Ayrshire's Labour-run council built four new schools a decade ago costing £81 million to build but requiring £401 million in payouts between 2007 and 2037.

He said: "That's the equivalent of buying an £81,000 flat, paying a mortgage of £1,114 a month for 30 years and then not even owning at the end of those 30 years."

The First Minister's comments came after she was urged to provide an "unequivocal guarantee" all school buildings are safe across Scotland after an investigation found 72 had safety defects.

An independent inquiry into school safety was commissioned after serious building deficiencies first came to light when a wall collapsed at a PFI-built primary school in Edinburgh last year, leading to the temporary closure of 17 schools across the city.

Ms Sturgeon said the inquiry found using PFI was not "in itself responsible for defective construction" but that implementation by the partners involved could have been stronger.

She said: "This whole episode has raised some serious questions for previous Labour administrations and one day perhaps they will have to answer and, yes, apologise."

She added: "None of the schools requiring remedial work were built under this government's current schools programme.

"These are historic school building projects but nevertheless we've got make sure that all school buildings are safe and and that lessons from previous PFI programmes are properly learned and implemented in the future.

"The government is absolutely determined that we will discharge our responsibility to do so."