A report by the Health and Safety Executive's Mines Inspectorate said the incident at Longannet could not have been predicted.

Energy Minister Brian Wilson said the government's �41m investment in the mine was on the verge of being rewarded when the flooding struck.

I deplore the campaign of scurrilous innuendo, unsupported by a shred of evidence, which has emanated from certain quarters since the flood occurred

Energy Minister Brian Wilson

"Longannet was lost as a result of flooding which could not have been anticipated and for which nobody should be held responsible," he said.

"I deplore the campaign of scurrilous innuendo, unsupported by a shred of evidence, which has emanated from certain quarters since the flood occurred.

"I hope that those responsible will now accept the Mines Inspectorate report and stop trying to exploit the misfortune of those involved."

The mine was shut after tunnels 250m below the surface were flooded in March.

Owner Scottish Coal (Deep Mine) was placed into liquidation and 330 jobs were lost when it was decided that it would not be economically viable to reopen the colliery.

Investigation launched

Some former employees raised questions about the source of the flooding, including allegations that sabotage may have been responsible.

An investigation was launched by the HSE within days of the incident.

A spokesman said that mine records were examined and 30 people were interviewed as part of this process.

"The inspectorate looked at the possibility of sabotage as a cause," said the HSE spokesman.

The mine was closed earlier this year

"The report rules this out, as the rate of flooding was much higher than would have been possible due to sabotage."

The report said that the flooding struck tunnels in the Castlehill Pit Bottom area of the mine.

The 15 people below ground at the time were three miles away in another part of the mine and were quickly evacuated.

An estimated 3.6m gallons flowed into the mine in the first 20 minutes at an average rate of 175,000 gallons per minute, blocking the ventilation circuit.

In two-and-a-half hours about 17m gallons of water had flooded into the mine.

No firm conclusions

The report said it was not possible to draw any firm conclusions about how the flooding occurred.

However, a failure in the area of the Castlehill/Solsgirth dam caused by water pressure is thought to be the most likely cause.

The report also concludes that none of the possible causes of the flooding could have been foreseen.

Mining (Scotland) Limited, the parent company of the Scottish Coal (Deep Mine), welcomed the findings.

"The conclusion that the dams were designed and constructed to standards well in excess of those required, and that interference with the structures as a cause of the flooding could be ruled out, confirmed the company's own conclusions based on regular inspections," said a spokesman