According to the ODA the levels found pose no threat to the workers clearing the site or to the public.

The 2.5 square-km site in east London was formerly home to light industrial premises and a 100-year-old waste tip. Several factories and workshops were known to be using radium paint between the 1930s and 1960s.

A report from the ODA's specialist contractor said the finds registered low or very low levels of radioactivity only slightly above normal background levels.

"Health and safety is our major priority. This report makes clear the health of the public or workers has not been put at risk," said ODA chief executive David Higgins.

"We do want to be open and transparent about our work cleaning up the site. That is why we are publishing this expert report, commissioned immediately after this find, which confirms this initial assessment.

"It is important this find is kept in perspective. It demonstrates our procedures are working and we are already acting on the recommendations from our experts to strengthen them further."