RUTH Davidson has suffered another blow to her leadership after her top donor's companies were put into administration.

KPMG last week took charge of three firms that are part of Edinburgh tycoon Malcolm Scott's business empire.

A spokesman for the Tory leader declined to comment, but party sources said the financial blows would mean Davidson's wish to create new internal posts would have to be funded by London.

Scott, whose fortune was made in the property and grain sectors, has donated around £1.6 million to the party in recent years.

After the exit of Lord Laidlaw amid a "sex addiction" scandal, Scott's mix of corporate and personal contributions made him the biggest donor to the Tories north of the Border.

He also hosted intimate dinners for high-profile Conservatives and is a close friend of Foreign Secretary William Hague. But his generosity has dried up amid the deteriorating health of his firms. The Sunday Herald revealed in November that five of the large firms he owns or controls were late filing their accounts.

On Thursday, administrators were appointed to take control of three property and investment firms in Scott's Dunalastair group. One of the firms, BS 1001 Limited, was Scott's holding company and lynchpin of his empire. It used to be called Dunalastair Philip Wilson Ltd and had a turnover of £34m in 2009. But the same year's accounts noted a "material uncertainty" which "cast doubt on the group's ability to continue as a going concern". The firm lists Scott as its majority shareholder and trades from a leased property in Edinburgh's Old Town.

The second firm is Prestonpans (Trading) Limited, which owns the West Port Hostel in Edinburgh's Grassmarket and a vacant property in the city's North Street.

BS 1003 Ltd, formerly known as Dunalastair Investments Limited, is also ailing. This firm owns property in Edinburgh's plush Rutland Square and Rutland Street. Administrator Gary Fraser said: "These businesses have suffered as a result of the very challenging conditions following [the] downturn in the property sector. " Other companies owned by Scott are not in administration.

The move gives Davidson another financial headache as she tries to transform her struggling party. She was stung last month when Sir Jack Harvie announced he was quitting as party fundraiser. The construction tycoon had raised almost £16m since the 1980s for the Conservatives.

Another donor, John McGlynn, has been critical of Davidson and has not signalled an intention to hand over any money.

He last week proposed 10 "budget ideas" to Chancellor George Osborne to get the economy moving. These included giving small firms a tax "holiday" if they invest the saving in their business, as well as backing a 100% corporation tax on banks that fail to meet lending targets.

He said: "What has Ruth Davidson suggested to the Chancellor? Does she have any ideas for the prosperity and health of Scotland?"

SNP MSP John Wilson said: "It is clear [the Scottish Tories] will have to rely on financial support from Conservative Central Office in London. This brings into question the level of autonomy Ruth Davidson will have in the future decision making on Scottish issues."

Labour MSP John Park said: "This is pretty embarrassing stuff for the Scottish Tories."

Scott could not be reached.