Shell is to cut 350 jobs in its North Sea operations following a review.
The company has reviewed offshore operations
Staff and unions were stunned by the scale of the job losses announced by the company on Monday.
The cuts will be among the company's own staff and contract workers on North Sea installations.
The Health and Safety Executive (HSE) said it would be working with Shell to ensure that the proposals did not threaten safety.
The announcement followed a six-month review of operations aimed at cutting costs and streamlining Shell's offshore business.
The oil giant said the jobs would be lost through natural wastage and voluntary retirement, although it accepted there would be some redundancies.
At present we invest over £1bn a year in the North Sea and it is vital for our industry that we remain internationally competitive
Marke Carne, asset director at Shell Expro, said: "By making these changes we will be able to prolong the life of our platforms and the jobs that are directly and indirectly dependent upon them.
"We will also improve our ability to attract future capital investment.
"At present we invest over £1bn a year in the North Sea and it is vital for our industry that we remain internationally competitive."
Unions fear that vital maintenance work will be cut on North Sea installations.
However, Shell said that only a very small proportion of the job losses would be maintenance-related.
Almost 1,600 people work in the area affected by the review.
Details of the re-organisation plans were given to staff both offshore and onshore in Aberdeen, Glasgow and Newcastle on Monday morning.
Workers and union leaders were stunned when they emerged from a series of briefings.
The Amicus AEEU union called for the HSE to intervene.
It is a short-sighted decision by Shell in that most of these people will now
be lost to the industry
Regional officer Graham Tran claimed that the new arrangements would reduce the number of maintenance checks and compromise offshore safety.
The GMB Scotland union also raised safety concerns.
Jim Moohan, the union's shipbuilding and engineering senior organiser, described the cuts as a "cruel blow".
He said: "It is a short-sighted decision by Shell in that most of these people will now
be lost to the industry.
"If things were to change for the better in the industry, it would mean them having to recruit new people and to train them at a very high cost."
A spokesman for the HSE said: "We are obviously concerned to ensure the staffing reductions planned by Shell do not threaten safety.
"We will be vigorously pursuing with Shell how they can achieve the improvements they need to make to their maintenance performance while reducing their staffing levels.
"HSE inspectors are meeting Shell today and will be holding the company to their commitment to make safety their top priority."