Heavy cuts in central government funding have left the authorities having to consider increasingly exotic solutions to ease their financial constraints.

Between 2010 and 2015, there was a 37% cut in real terms in central government funding to local authorities. One option – popular in the last couple of years – has been to borrow from the Treasury-run Public Works Loan Board (PWLB) at very low rates of interest and then use the money to invest in commercial property ventures that offer returns of as much as 8%.

But there are fears that the strategy is creating a bubble that could bankrupt some local authorities. “This is not a wise and sensible thing to do,” said Cable, who was business secretary in the Tory-Lib Dem coalition and is standing as Lib Dem candidate in his former seat in Twickenham, south-west London.

“Local authorities have a long and inglorious history of gambling in financial and property markets,” he said. In the 1980s, Hammersmith and Fulham council was one of several local authorities that got into financial difficulties after becoming involved in complex bets on interest rates.

Cable said he could understand why councils were considering such strategies. “When they are massively constrained in what they can do around council tax – and indeed commercial rates – they are trying to prevent even deeper and more damaging cuts by taking these unorthodox measures. In some cases they may succeed, but there is a very high risk of bankrupting their local authorities. It does suggest a certain degree of desperation.”

Local government sources have defended the councils, saying that much of the money is invested in helping regenerate their local areas. But not in all cases. “What is so bizarre, so shocking, is that they are investing in property in other parts of the country,” Cable said. “It makes no sense whatsoever.”

Matthew Oakeshott, an investment manager at Olim Property, said councils were “playing a gigantic game of Monopoly with taxpayers’ cash”.

But authorities badly need returns at a time when interest rates remain low and demands on councils are rising. It is estimated that, by 2020, England’s councils will face a near £6bn funding gap between what they need to spend and what they receive. Most of this shortfall is due to rising costs linked to social care.

Two years ago, the Local Government Association warned that a dozen councils were on the brink of financial failure. Since then, the councils have had to be inventive in seeking to balance their books. Several – such as Eastleigh, Kettering and Maidstone – have successfully exploited loans from the PWLB to invest in commercial property. This, in turn, has attracted interest from other councils.

But such copycat behaviour is a concern, according to Cable, who drew comparisons with 2008, when many councils were left exposed after depositing millions of pounds in high-interest rate accounts offered by Icelandic banks, which then went bust.

“It did very serious damage to some councils,” Cable said. “It should have been a warning to all corporate treasurers in local government to not go anywhere near this.”

The extent to which councils are exposed to a downturn in the commercial property sector is unclear.

Last month, Lord Myners tabled a parliamentary question asking the government to confirm how much money the PWLB had lent to local authorities to invest in commercial real estate between 2011 and 2016, and what it was doing to monitor the risk from such investments.

Responding for the government, Baroness Neville-Rolfe said it was up to the councils to assess risk. She said: “The Public Works Loan Board is not required to collect information on the specific reasons that local authorities borrow from it, and so it does not hold information about the amount of lending that has been used for acquisition of commercial real estate.”

However, estate agent Savills told the Financial Times that councils had invested £1.2bn in commercial property last year and a further £221m so far this year.

An economic downturn could see commercial property yields drop, leaving councils exposed, say analysts. This fear has led some councils to resist investing, but others have developed considerable appetites. The Financial Times reported that Spelthorne borough council – which has assets of just £88m – bought a business park in Sunbury-on-Thames for £360m, having taken out 50 separate loans from the PWLB.

Local government sources played down fears of a bubble, pointing out that every council investment was made on a case-by-case basis and had to meet strict borrowing criteria.

Under the Prudential Code, councils must show that their investment plans are affordable, prudent and sustainable.