The Olympic Delivery Authority (ODA) has begun clearing Japanese knotweed from the site of the Olympic Park — the main complex for the 2012 London Olympics. The plant, which can crack through concrete and overpower native plants, was discovered on 2% of the site. “Cleaning up the Olympic Park site is a challenging job and we’re starting with one of the toughest plants in the world,” said ODA chief executive David Higgins.

The Japanese knotweed was found along the river and canal banks, the Velopark and beside the Aquatics Center site designed by Zaha Hadid.

Tackling Japanese knotweed is included in the remediation and demolition budget and will not add to the overall ODA budget announced earlier this month.

Contractors have dug over 1,300 bore holes and investigated three-quarters of the site and to date have found nothing unexpected. Investigations are continuing and the full clean-up starts this summer when the full site becomes available. The cleanup expected to be completed before construction of the Olympic Park begins in 2008.