Strathclyde is Scotland's largest force and faces many demands
A cash shortfall faced by Scotland's biggest police force could grow as large as £34.7m, it has emerged.
The warning about Strathclyde Police came from the convener of the force's police authority, Paul Rooney, who outlines a "dire financial situation".
It is understood that, at best, there will be a £12.4m hole in the budget. At worst, it could reach £34.7m.
Opposition parties said the issue could hit frontline policing and called on the Scottish Government to help.
Ministers said they had given councils record funding of £23bn to deliver services, and funding for 1,000 additional police officers.
The Strathclyde Police Authority, which sets and monitors the force budget to ensure it delivers value for money, will discuss the issue this week when considering a report on next year's budget.
Mr Rooney, said: "This report sets out, in the bluntest terms, the dire financial situation faced by the police service in the coming years.
"Over the last two years, Strathclyde has made significant efficiency savings, diverting every available penny of our budget to ensure record numbers of police officers are out on our streets.
"For the first time ever, Strathclyde has more that 8,000 police officers and we are 100% committed to retaining this number in the coming years."
He added: "Unfortunately, the police authority has some very difficult decisions to make in terms of how we plug this massive funding gap. Even if tougher efficiency savings are considered the gap remains significant."
Labour justice spokesman Richard Baker said: "This budget blow will damage frontline policing unless the SNP inject some serious cash.
"The progress made in police recruitment in Strathclyde has largely been funded by local authorities not central government and now it's up to the SNP to stump up.
"There is no point pledging extra officers if numbers are cut in years to come."
Robert Brown, of the Lib Dems, added: "The SNP needs to reassure the public that community safety won't be jeopardised by this black hole in police funds.
"Justice Secretary Kenny MacAskill must meet police chiefs urgently to make sure that key promises, for instance boosting police recruitment, will go ahead."
The Scottish Government said its action meant police numbers were at a record high - more than 17,000 - and were expected to keep rising.
A spokesman added: "We've also funded police wage rises in recognition of the valuable service they provide, and have met the pensions requirements of our forces, following the pensions deficit we inherited from the last government.
"We are fully committed to delivering a more visible policing presence, which deters crime, reassures our citizens and keeps our communities safer."