Laughing gas canisters have been found among the ducks at the popular nature trail at Bluewater.

Half a dozen canisters, which contained the anaesthetic gas nitrous oxide, were discovered near the Greenhithe shopping centre.

Although it is sometimes taken as pain relief for dentistry or childbirth it is also used as a recreational drug.

It is one of the most used drugs in the UK, particularly among young people.

But it can cause dizziness and could be deadly if taken in large amounts over a short period of time.

A Bluewater spokesman said: "Safety of our guests is paramount at all times.

"The Nature Trail is incredibly popular with our guests and it is regularly patrolled and cleaned."