Expanding swarms of jellyfish are causing costly damage to coastal economies worldwide, but Korean scientists have come up with a radical solution to the problem: a flotilla of robots armed with nets and shredders.

Experts at the Korea Advanced Institute of Science and Technology in Daejeon, South Korea, began work on the so-called Jellyfish Elimination Robotic Swarm in 2009.

The machines are fitted with a camera that allows them to detect jellyfish near the surface.

They then drop a net and drag the creatures into a giant shredder, removing 360kg (800lb) of jellyfish an hour, according to Professor Myung Hyun, the lead scientist on the project.

Jellyfish are resistant to many forms of poison, and dead jellyfish can clog up pipes, which led scientists to experiment.

A recent trial of three robots in Masan Bay, South Korea, proved a success, and scientists are now working on ways to manoeuvre a small group of the robots in tandem, which would allow them prevent shoals from breeding and expanding.

"Recently, the increase in population of jellyfish is becoming a great menace to the ocean's ecosystem, which leads to drastic damage to the fishery industries," said Professor Hyun.

"The prototype of the system was implemented, and its feasibility was demonstrated through outdoor experiments and field tests."

Experts believe that global warming, pollution and overfishing may all be linked to the rising numbers of jellyfish worldwide.

Only last week a swarm of jellyfish clogged a pipe bringing sea water to cool turbines in Oskarshamn nuclear facility, Sweden, forcing the whole plant to close down temporarily.

In South Korea, jellyfish are believed to cause $300 million every year in damage and losses to the fishing industry.

The creatures are also wreaking havoc in other parts of the world. Ireland's only organic salmon fishery was wiped out by jellyfish in 2007. Off the coast of Namibia, jellyfish biomass exceeds that of sardines and anchovies by more than three to one, causing enormous damage to the local fishing industry.

One Japanese nuclear reactor removes 150 tonnes of jellyfish every day.