TWO thousand jobs could be lost to Scotland because six major oil companies have decided to shelve plans for the Clair oilfield development west of Shetland.

The Herald has learned that it has become the first casualty of uncertainty in the oil industry, anxiously awaiting the publication of the Government's proposed tax changes.

The industry fears these changes could threaten an estimated 50,000 UK jobs.

The six partners in the development will announce this week that it is being put on long-term hold. It is estimated that the development could have created about 2000 jobs directly and indirectly, including the construction phase.

A spokesman for one of the group, BP, confirmed last night that the uncertainty was making it ''very difficult to maintain momentum'' and that as a result the partners would not be seeking development approval in 1998 as was intended.

Although Clair is the most high profile casualty of the as yet unspecified tax changes, they are already said to be having a significant impact on the industry.

The United Kingdom Offshore Operators' Association and the Offshore Contractors' Association have spent a year lobbying the Government to try to make it aware of the impact of any tax rises.

The Herald understands that although the partners, BP, Chevron, Conoco, Elf, Enterprise and Amerada Hess, refer only to 1998 the development proposals could be shelved indefinitely unless the tax changes are considerably kinder than is feared.

Just two days after the Budget it was announced that an oil pipeline would be laid from the west of Shetland to Sullom Voe if Clair were developed.

BP told the terminal operators they would enter an exclusive agreement with them.

The Clair Field was discovered 21 years ago and sits in 150m of water. It is the largest Atlantic find so far and contains an estimated four to six billion barrels of oil.

However, of the estimated four billion barrels in the highly successful Forties Field around 2.6 billion are recoverable, but in Clair the current figure is only 200 to 300 million barrels.

It is only advances in drilling and seismic technology that have made the partners consider trying to overcome the huge engineering obstacles they face.

Clair's go-ahead would have seen the requirement for two steel platforms from the country's oil yards which have extremely lean order books.

However, the possibility of a tax rise has, apparently, denied them that work.

In the March Budget, the Government announced two different proposals for increasing tax but said it was inviting comment or alternative suggestions to ensure a high level of activity was maintained.

It said a consultative document would be published in the middle of April with the aim of legislation in the next Finance Bill.

The industry stepped up its lobbying, which included a recent letter to Mr Tony Blair.

The consultation document has still not been published, and the rumours about when it will come out vary from days to weeks.

There is also speculation that the civil servants have been convinced of the arguments, but the politicians less so.

The consultative document will provide an analysis of the level of taxation of North Sea profits and the impact of taxation on expected returns from exploration and will compare the North Sea tax system with that of other countries.

If it does, as announced, propose two options, the first will be the introduction of a supplementary corporation tax charge on the profits from UK oil and gas extraction activities.

It would be charged on profits within the existing ''ring fence'' for these activities, and profits would be determined before the deduction of any financing costs, including interest.

The second option will be to extend Petroleum Revenue Tax to all fields given development consent on or after March 16, 1993 - fields which are currently not liable for PRT.

The oil allowance, a PRT-free slice of production for all fields, would be halved and a new PRT relief would be introduced to give companies relief on abortive exploration expenditure.

Both packages would include the abolition of oil and gas royalty which would encourage the maximum exploitation of older reserves; the removal of Tariff Receipts Allowance; and the relaxation of the timetable for the delivery of PRT returns.

In the current climate of uncertainty, the Clair partners have decided that it is not financially viable to develop the field