Conservative Party supporter Alasdair Locke has signalled that record results for his Abbot Group could have been even better without tinkering in the North Sea by Gordon Brown, and says that he prefers the Scottish Nationalists to Labour.

The oil services leader provided further help for the Scottish National Party by dismissing Tony Blair's criticism of Sir George Mathewson's declaration of support for independence as "insulting in the extreme".

Coming days after Mathewson, a former chairman and chief executive of Royal Bank of Scotland, endorsed SNP leader Alex Salmond for First Minister, the latest contribution to political debate by Locke may be a welcome surprise for the SNP.

While the Prime Minister described Mathewson's claims that Scotland could go its own way successfully as "pure self-indulgence", Locke appeared to side with the veteran banker. "Of course Scotland can stand on its own, and it's very insulting to say it can't," Locke told The Herald.

However, other comments made by Locke indicated he was motivated by longstanding concern about the effects of increases in taxes on North Sea profits under the Labour government, rather than an unexpected conversion to the cause of independence.

Salmond, a former oil economist for the Royal Bank of Scotland, has repeatedly accused Gordon Brown, the Chancellor of the Exchequer, of raiding the North Sea to boost the government's coffers at the expense of the interests of a vital industry.

"I have been noted as being a Conservative supporter, but if you were rating Labour and the Liberal Democrats and the SNP, Alex Salmond is clearly a better performer than either of those two," said Locke.

He was speaking after Abbot became the latest services company to post bumper earnings on the back of strong oil and gas prices, with a 55% increase in earnings before interest, tax, depreciation and amortisation, to $155m (£80m).

The Aberdeen-based company said that activity levels had increased in the North Sea, where it had 10 rigs operating at the year ended December 31.

Based on this measure, activity has more than doubled since 2004. The number of offshore rigs operated by Abbot in the North Sea fell to an all-time low of four in that year, after Brown imposed a 10% premium on North Sea taxes in 2002.

Last January, following the chancellor's decision to double the premium to 20% in the preceding month, Locke said Brown deserved an antisocial behaviour order.

Locke even claimed that successive tax changes would cause a disastrous flight from the province.

However, Abbot said yesterday that its RDS rig design and engineering business had benefited last year from increased activity in the North Sea by firms that were looking to improve the performance or extend the life of older fields.

But calling for Brown to leave the oil and gas industry alone in his Budget tomorrow, Locke denied that the upturn invalidated his criticism of the government.

"As you would expect, the tax changes of a couple of years ago are bearing fruit in making the UK one of the least attractive places to invest," he complained. "Activity has increased to a small extent, and it will increase this year, but it's far less than it should be. The tax changes are skewing investment so you are not getting the investment that you should be for future development."

Abbot continues to describe the North Sea as a core area, but has been focusing investment overseas in areas like the Caspian and west Africa, which are attracting increased interest from oil and gas majors.

With strong demand for oil and gas in the fast-growing economies of India and China and developed countries like the US, the outlook for services firms is bright.

After growing turnover 70% to £603m in 2006, Abbot already has 96% of its budgeted revenue for 2007 secure.

Locke said Abbot would invest about £100m in supporting organic growth this year.

The company, which has completed two big acquisitions in recent years, is keeping its eyes open for suitable purchases but does not have any deals on the go.

Shares in Abbot closed up 13p at 293p. That gave the company a market capitalisation of £682m, valuing Locke's 12.9% holding at £88m.