MORE than 5,500 jobs have been lost in the North Sea energy industry since oil prices plunged with many more set to go in the coming years, industry experts have warned.

The estimate comes amid fears that the oil price drop, which began a year ago and saw the price more than halve to less than $50 before making a slight recovery, may stagnate for years to come as part of what may become the worst global oil crash in almost half a century.

Oil and Gas UK warned the estimate of 5,500 jobs may be conservative while Unite, the trade union that represents many workers in the industry, put the total at least 4,000 and warned cuts to numbers could put safety of remaining employees at risk.

Meanwhile, around 1,700 people have attended jobs events organised by a Scottish Government taskforce to help workers find jobs.

However, there was also predictions of a "silver lining", with many firms turning to innovative new methods to boost production and increase efficiency, leaving them well-placed to ramp up production in the years to come.

Deirdre Michie, chief executive of Oil & Gas UK, said the industry was doing all it could to ensure the sector was " safe, competitive and sustainable in a world of $60 oil" but admitted the plummeting price coupled with increased costs had led to "a major impact on activity" which inevitably meant bosses had been left with tough decisions.

The price for Brent Crude Oil fell below $55 last week for the first time in months, having remained at around $110 between 2010 and the middle of last year. The reintergration of Iran, with the lifting of sanctions as part of a deal on its nuclear programme, could reduce the price further as its oil adds to a glut of supply in the international market and significantly delay any recovery.

Ms Mitchie said: "We are applying the lessons we have learnt from the past and we know that our focus cannot merely be on ‘cutting costs’. In a more profound and universal way we must address the efficiency of the basin so that, if or when the oil price bounces back, we will be best placed to seize new opportunities."

Firms are slashing jobs as they struggle to balance the books. BP, Royal Dutch Shell and Total are among those reducing staff, while investment and projects previously set to go ahead have been put on hold. Last year, North Sea exploration reached its lowest level in at least two decades, with only 14 explorations wells drilled, compared to 44 in 2008.

Alex Kemp, professor of petroleum economics and director of Aberdeen centre for research in energy economics and finance at Aberdeen University, said it was impossible to pinpoint the total number of job losses but that the 5,500 figure was plausible.

He added: "There has had to be major reassessments and cost reducing initiatives, and that's going to continue this year and beyond. Some cutbacks are linked to completion of contracts, meaning that rather than breaking contracts they are not renewed. That will continue.

"We've done modelling which shows that a $70 dollar price, there will be much less investment than at $90. Tax concessions in the budget may be worthwhile in the medium term, but a lot of new projects are not viable with zero tax. Something like $70 could be the position for several years ahead."

However, he agreed that a "silver lining" could emerge as North Sea oil firms become more efficient. "The next couple of years will be very tough, but the industry will emerge leaner and healthier for the long term," he said. "It's not the end of the story, there are enough reserves there for the industry to last quite a long time but at the moment, cost savings are essential."

Pat Rafferty, the Unite Scottish Secretary, hit out at the industry's "failure to plan for a rainy day when the sun shone" and claimed the previous complacency was leaving thousands to "pay with their livelihoods".

He added: "Oil firms have received £1.3 billion in tax breaks, but are still cutting jobs which could ultimately impact on health and safety. Over the longer term, we have major concerns about a brain drain and there being a lack of skills and expertise in the industry for when oil prices begin to recover."

A Scottish Government spokesman said the sector employed 200,000 people and that Scotland remained a "global leader" in the oil and gas industry.

He added: The North Sea remains the largest oil and second largest gas producer in the EU by a considerable margin and Scottish based oil and gas supply chain companies delivered a record £22.2 billion of supply chain sales during 2013.

"We have successfully campaigned to have the misjudged increase to supplementary charges reversed and the First Minister has also called for further action from the UK Government to incentivise exploration, promote stability across the industry and boost investor confidence."