An emergency operation to move 25,000 fish has been carried out after an outbreak of a deadly algae on Hickling Broad.

Officials from the Environment Agency (EA) sprang into action on Thursday following reports of hundreds of dead fish in the broad.

Anglers fear the algae, prymnesium parvum, could spread and decimate fish over a much wider area, jeopardising a multi-million pound driver to the Broads tourism industry.

And last night, leading pike fishing spokesman John Currie said he was receiving reports by the hour of more dead fish turning up in nearby Catfield.

Estimates of the number of dead fish, mainly perch, are rising all the time and Mr Currie, a regional organiser for the Pike Anglers Club of Great Britain, fears the death toll will reach the thousands.

He said: 'A lot of the carcasses won't be washed up. Fish found dead so far have included 5lb perch which most anglers would regard as a fish of a lifetime.'

Mr Currie observed the EA operation in the dyke at Hickling's Whispering Reeds boatyard where weakened fish, mainly roach, had gathered.

He said: 'First they used aerators to increase oxygen levels in the water and then they carried out three or four sweeps of the dyke using 100-metre nets.

'The fish were then put in aerated tanks on the back of trailers and taken to areas of the Thurne safe from prymnesium.'

Anglers have been acutely aware of the deadly danger of prymnesium since a large-scale outbreak in 1969 devastated fish stocks throughout the Thurne system.

Warm weather is known to be a trigger for algal blooms and there is evidence to suggest that disturbing sediment at such times can heighten the risk.

With this danger in mind, Mr Currie called on the Broads Authority to stop excavation work in Heigham Sound, on the edge of the broad, during warm-weather conditions.

The authority is excavating sediment to recreate a lost island at the entrance to Duck Broad as a creative solution to deepen the channel for boating.

Anglers have long been concerned about the risks of the operation and Mr Currie said: 'Why take the chance during warm weather when they can wait until the winter? Anglers are just as big a stakeholder on the Broads as boaters and we are not being shown a proper duty of care.

'The Broads Authority's own studies show fishing brings more than one million people into the area annually contributing �70m to the economy.'

A Broads Authority spokesman last night downplayed any possible link between the prymnesium outbreak and work going on at Heigham Sound.

She said: 'Prymnesium levels have been regularly monitored and found to be within safe levels.'

She added that it was at least a mile away from the area of Hickling Broad where the dead fish had been found.

EA fisheries officer Steve Lane said a bloom could be the result of a combination of factors, but the conditions at Hickling Broad had been just right with rising temperatures and clear skies.

He said: 'We have managed to rescue a large number of fish in distress and will be closely monitoring the situation over the weekend.'

'We would urge anyone who sees dead fish to ring our hotline number 0800 807060.

Jason Van-den-Burg, an employee at Whispering Reeds, said local people had been reporting small dead perch being washed up over the past two or three weeks.

Peter Benjamin, who has lived in Hickling for nearly 30 years and seen the impact of previous blooms, said: 'I did not notice anything when I went up to Horsey on our motor cruiser 10 days ago but there are a lot of dead fish in the broad now, including bream and pike as well as perch.'