Enron employs 900 workers at three Teesside plants
US-based Enron is on the verge of bankruptcy after a £5.9bn rescue bid was terminated.
On Thursday the European operation was split from its U.S. parent and placed in administration with PricewaterhouseCoopers.
Enron employs 3,700 workers in the UK, including 900 at three power plants on Teesside and 1,400 at Wessex Water, as well as a further 5,000 across Europe.
PWC said there may be job losses in Europe, but could not say where. But they said the Enron administration order does not include its Teesside power plant.
Enron's problems came when rival firm Dynegy pulled out of merger talks, which would have saved Enron from a financial crisis which has seen its shares collapse by 90% in two months.
In the North-East, Enron owns a gas processing plant at Seal Sands, the Teesside Power Station at Grangetown, and a utilities business at Wilton.
Mike Brider, Teesside senior regional industrial organiser with the Transport and General Workers' Union (TGWU), told BBC News Online: "I am more confident than I would be if I was in another part of the globe.
Rescue hope
"When ICI sold these plants on Teesside to Enron there were a number of buyers on the market for them.
"I think the Teesside enterprise and the workforce can survive."
But Jimmy Skivington, organiser for the GMB in the North-East, told BBC News Online: "It is an extremely worrying time for our 100 contract workers in the Teesside plants.
"Hopefully someone will come forward with a rescue package."
Wessex Water employs 1,400 workers and serves millions of customers in Wiltshire, Dorset, Somerset, Hampshire, Devon and Gloucester.
They said whatever happened at Enron would have no effect on Wessex's services or its financial position.
Independent operation
Officials reassured customers and staff that it was "business as usual" despite the dramatic developments at its Houston-based owner.
They said: "Wessex Water is ringfenced as a regulated business and operates independently.
"Whatever happens to Enron will have no effect on its services or its financial position."
They said any new owner would have to satisty the company and Ofwat it had the best interests of customers in mind.