Dutch oil giant Shell plans to cut nearly 500 jobs from its North Sea workforce.
The announcement on Wednesday came as the result of a £47bn merger with the BG Group.
All 475 jobs are expected to be lost by the end of the year, mostly from Shell's Aberdeen headquarters.
Another 4500 posts will be shed worldwide.
It is believed to be one of the largest single announcements of North Sea job losses in recent years.
UK and Ireland Shell vice-president Paul Goodfellow said: "We're continuing the improvement journey we've been on to create a competitive and sustainable business in the North Sea.
"Despite the improvements that we have made to our business, current market conditions remain challenging.
"Our integration with BG provides an opportunity to accelerate our performance in this 'lower for longer' environment.
"We need to reduce our cost base, improve production efficiency and have an organisation that best fits our combined portfolio and business plans.
"As a result, we will reduce the size of the organisation supporting our UK and Ireland Upstream business by around 475 people. We will look to implement the majority of this change during 2016.
"Following these changes, Shell will still remain a key employer in the north east of Scotland with around 1700 employees."
Unite warned that if the current rate of jobs losses in the oil and gas sector continues, there will be no viable North Sea oil industry within a decade.
Regional officer John Boland said: "We have very real fears that Shell cannot continue to operate safely offshore if it keeps shedding the workers tasked with ensuring our oil industry is safe and sustainable.
"The Oil and Gas Confederation (OGC), of which we are members, has called time and again for an oil and gas sector summit to be convened urgently.
"So far the call has fallen on deaf ears but both the Scottish and Westminster governments must wake up to what is happening to this vital sector.
"They cannot stand by while a vital industry's demise takes place on their watch."
Shell expects to have cut 12,500 jobs globally since the start of 2015 by the end of the year.