A foreign insect is to be released into the UK in an effort to bring an invasive plant under control.

Japanese knotweed, which grows through concrete, damages buildings, roads and kills flowers, can grow up to a metre a month.

The problem plant costs tens of thousands of pounds to keep under control in Leicestershire alone.

Yesterday, the Government gave the go-ahead for the release of a tiny sap-sucking insect, which is a predator to the rampantly growing plant in their native Japan.

The announcement was being celebrated by the University of Leicester.

They carried out a pioneering study which helped pave the way for the first trial in a Europe of the "biocontrol."

Dr John Bailey, from the university, has been studying knotweed since the 1980s and has been on field trips to the Nagasaki area of Japan to see the 2mm psyllid Aphalara itadori – a species of jumping louse – in its own environment.

He said: "It's excellent that the trials are going to go ahead.

"This will be the first release for a plant-based predator so it will be a bit of a test case.

"When we started research it was intended as a curiosity study – now it has acquired a real importance."

Extensive tests have been carried out on the Japanese insects to ensure they will not have a detrimental affect on Britain's wildlife. The research suggests the psyllid would only target the Japanese knotweed and a few other closely related, non-native species if it were released in the UK.

Japanese knotweed is labelled by the International Union for Conservation of Nature as one of the world's 100 most invasive species and the Government estimates it costs more than £150m to control and clear it each year in the UK.

Conventional schemes to rid the countryside of the plant require treatment with herbicides, physical removal and treatment to ensure it does not grow back.

It is hoped the introduction of a species of psyllid insect to several sites across the UK will act as a form of natural pest control.

Adrian Lane, Leicester City Council's riverside officer, said the weed was a difficult one to control.

He said: "We have significant amounts of it on Leicester's rivers. It takes an awful lot of effort and resources to control it.

"It is not spreading but it is a continual effort to keep on top of it.

"While I'm usually quite cautious about biological controls, there seems to have been a lot of testing with this. It could be the weapon we need."

Environment minister Huw Irranca-Davies has not yet announced at which sites the Japanese lice will be tested.

It will be intensely monitored for several months and if successful will be rolled out to other areas of the country.