Work on a new Oxford primary school has been stopped after a plant capable of destroying concrete was discovered on the site.

Japanese Knotweed has been discovered on land earmarked for the new £3m SS Philip and James Primary School, in Aristotle Lane, north Oxford.

The new building is being constructed in time for the re-organisation of Oxford's schools, in September next year, which will see first, middle and upper schools replaced by primary and secondary schools.

SS Philip and James First School is on a cramped site in nearby Leckford Road.

The school's headteacher, Irene Conway, said: "We'd have had to clear the site anyway and we're not that worried about it."

Subcontractors are now clearing the area with chemicals and by digging up the greenish-white flowered plant, which can grow to 3m tall.

It can damage concrete and paving as it grows into dense thickets.

The weed is capable of surviving drought, high temperatures, fires, shade and flooding.

It can also cause other problems, including over-shading native plants, soil erosion and a reduction in land prices.