The battle to prevent an alien invader from smothering large stretches of the Norfolk and Suffolk Broads was in full swing yesterday as Broads Authority staff took to the water in Diss.

The battle to prevent an alien invader from smothering large stretches of the Norfolk and Suffolk Broads was in full swing yesterday as Broads Authority staff took to the water in Diss.

Work is being carried out on the River Waveney to get rid of the fast-growing floating pennywort.

If left unchecked the plant, which originates from North America and grows up to 20cm a day, could spread and clog up the river systems.

Once it takes hold it can grow up to 15m in just one season causing large parts of waterway to be submerged by the life-chocking de-oxygenating vegetation.

The plant has started to take root in the Rockland Broad on the River Yare and the River Waveney near Diss since last Autumn.

To stop the invasion a £17,000 fightback has been launched by the Norfolk Non-native Species Initiative.

Volunteers have been meticulously removing remaining plants and any tiny fragments which can still root and re-grow.

Dr Dan Hoare, waterways conservation manager for the Broads Authority, said: “The plant was found in this area in November 2007 and almost immediately efforts were made to eradicate it.

“The plant comes out over the water surface and grows out from the bank. It affects wildlife and other plant life by blocking out the light. Fishing becomes impossible and it has a choking or strangling effect. We want to get rid of the plant to safeguard the future of the River Waveney and to prevent it from spreading.”

The Broads clean-up campaign is being funded by Defra, the Environment Agency and the Broads Authority and follows similar work on the Beccles Marshes in 2005.

The plant is growing in Diss and yesterday work was being carried out along a stretch of the river behind builders merchants Jewsons in Victoria Road. But Dr Hoare said patches had also been found at Scole, Billingford and Hoxne.

“This is an ongoing, long term-project in order to make sure this plant doesn't come back and to protect the Broads,” he said.

Floating pennywort was first introduced to Britain in the 1980s for tropical aquaria garden ponds and was first spotted in the wild in Essex in 1991.