The Food Standards Agency (FSA) has issued a Food Alert warning customers to return all products bought in the Waitrose organic free-range egg range.

The notice affects items with date codes up to and including May 20, 2008. No other Waitrose products are believed to be affected.

A Waitrose spokeswoman said: "We can confirm that some chickens from a flock on one farm supplying Waitrose with Blacktail Columbian Organic Eggs have been found to have consumed lead shot.

"This is thought to have been caused by shot from a nearby clay pigeon shoot getting into the free range enclosure.

"Waitrose took action as soon as we knew about this situation. All our eggs are fully traceable back to their farm source which is stamped as a code on each egg.

"As a precaution we are recalling extra large, large and medium organic Blacktail Columbian Organic eggs with the code of OUK20137 (stamped on each individual egg).

"This recall applies to all datecodes up to and including May 21. Customers are advised to take any affected eggs back to their local branch for a full refund. We apologise for any inconvenience."