Conditions at seven old opencast coal mines across Scotland's central belt are deteriorating, with growing risks of pollution, flooding and accidents, according to confidential documents seen by the Sunday Herald.

Mines in Ayrshire, Lanarkshire and Fife, abandoned by Scottish Coal when it went bust in April 2013, are threatened by rising water levels, contaminated lagoons and erosion. But money to look after them is running out, and it is far from clear where it will come from in the future.

Environmental and community groups say that there's now a "national crisis" over the worsening state of Scotland's opencast mines. It is putting local communities in danger and jeopardising the country's international reputation for conservation, they warn.

Four mines in East Ayrshire, two in South Lanarkshire and one in Fife are now under the control of Scottish Coal's liquidators, accountancy giant KPMG. But it has been struggling to find a new owner who would take responsibility for looking after them.

In a letter to creditors on May 23, KPMG warned that "remedial works have increased in number and scope as the conditions on the sites deteriorate". This was particularly due to rising water levels caused by heavy rain last winter, it said.

It had devised a programme of repair operations over the summer, and stressed that there had so far been no significant breaches of health and safety rules. "However, with the passage of time the ongoing inherent risk of a health and safety or environmental incident on one of the sites rises," it said.

KPMG's letter also recounted the difficulties it had had in selling off the old mines. A bid for them by a specially formed company, Scot Coal Energy Limited (SCEL), was twice rejected by the Scottish Environment Protection Agency (Sepa) because of concerns that pollution permits would be breached.

"The rejection of transfer applications is extremely disappointing and means that any material return to the creditors is now highly unlikely," said KPMG. It reported that it had about "funds in hand" of £8 million, though this was being constantly depleted.

The plan now is to transfer ownership to a new Government-initiated company called Mines Restoration Limited (MRL), which KPMG pointed out was "unfortunately" requiring a payment of between £2m and £4m. "While, on the face of it, this is not an immediately attractive option, in the context of alternatives available we believe it is the best course of action," KPMG said.

Last year, KPMG tried to disclaim any responsibility for cleaning up the opencast mines it inherited as liquidators, said to be costing £500,000 a month. But this was blocked by a successful joint court action by Sepa, the Scottish Government and local authorities.

Further evidence on the poor state of some of the old mines comes from a report in support of SCEL's failed bid to take them over. Dated February 26 and marked "confidential" on every page, it listed a series of problems at five mines.

At Mainshill, in South Lanarkshire, two quarries were "expected to overflow" because pumping had been discontinued, it said. Some water was contaminated, and "lagoon cleaning" was needed.

At Spireslack, in East Ayrshire, water was accumulating and there was "potential pollution" from a former barrel washing area, the report said. At Blair House, Fife, pumping had stopped, water was rising and a diverted burn was suffering erosion.

A huge hole at Powharnal, inEast Ayrshire was filling up at a rate of half a metre a month and there was a plan to "direct the overflow into the River Ayr", the report said. Water was also accumulating at neighbouring Dalfad, where "lagoon cleaning needs to take place".

"It is very frustrating to learn that these sites are still deteriorating over a year after Scottish Coal went bust and left dereliction and chaos in its wake," said Aedan Smith, head of planning at the Royal Society for the Protection of Birds (RSPB) in Scotland. It is concerned about the protected wildlife areas around mines, and has been scrutinising developments.

"Scotland has a legal and moral obligation to protect these areas and our international reputation for environmental stewardship is at stake," Smith argued. "This is a national crisis and we urgently need to see more leadership and action from the Scottish Government on this issue."

RSPB was pleased that Sepa had rejected the SCEL bid, and thought that handing it over to the new company MRL "could be good news". But Smith added: "We need a clear plan for restoration, and all available remaining funds must be transferred quickly from KPMG along with the sites to allow MRL to get on with the challenge of securing and restoring them."

Malcolm Spaven, who chairs the Scottish Opencast Communities Alliance, warned that the derelict mines were becoming more dangerous and more polluting. "Conditions at many opencast coal sites are getting worse," he said. "Once again it is local communities and the environment that are coming off worst."

Spaven accused ministers of ignoring solutions that would achieve genuine restoration and work for local people. "The Scottish Government has failed miserably to get a handle on the mess that the opencast industry has created," he said.

The Scottish Government pointed out that it had helped set up MRL, which was now in "advanced discussions" with KPMG to acquire seven sites. "KPMG is resolute that these sites are maintained safely over the period of their ownership," said a government spokesman.

The Scottish Government argued it would be inappropriate to comment further as negotiations have not yet been completed. A spokesman for MRL took the same line, as did KPMG, though it added: "It is hoped that a transaction will be concluded in the short term."

Sepa said it was currently considering applications by MRL and KPMG to transfer environmental licences for the seven mines to MRL. According to one official, there had only been one "marginal failure" in discharges from the East Ayrshire mines in the last 12 months and that had been "quickly rectified" by KPMG.