Poppy seeds widely used in UK bakery products may contain potentially hazardous levels of morphine, scientists have warned.

The seeds, which are commonly used in muffins, salads and pasta and sprinkled on bread, do not naturally contain opium alkaloids such as morphine. However, they can be contaminated from compounds in the stalk and seed capsules.

The Food Standards Agency (FSA) said "morphine-like" effects were observed in some consumers after they had eaten poppy seeds, The Sunday Times reported.

Scientists analysed 1,033 samples of poppy seeds and bakery products that contain the seeds, and warned that consumers, particularly young people, could potentially be at risk.

The FSA will issue UK poppy growers with new guidelines on cultivating and processing their crops in order to minimise any potential exposure to consumers.

French bread
Poppy seeds used in bakery products such as bread could contain potentially hazardous levels of morphine. Reuters

"If poppy seeds are consumed as condiments or decoration in bread and fine bakery ware, it is possible that some consumers, particularly toddlers, will exceed the [acute reference dose] for morphine on rare occasions," scientists said.

Drugs company Macfarlan Smith is the biggest producer of poppies in Britain, and operates plants under a Home Office licence in Oxfordshire, Hampshire, Dorset and Lincolnshire for the production of morphine.

It also produces around 1,200 tonnes of poppy seeds for culinary uses every year. The company said it strictly complies with the highest production standards at its plants, and that seeds processed at its premises are not at risk of morphine contamination.

"We use very stringent processes and there is no risk to the consumer. The cleaning processes are 99.9% purity," Jonathan Gibbs, head of poppy growing operations at Mcfarlan Smith, told the Sunday Times.

Poppy seeds are banned in a number of countries around the world, including the United Arab Emirates and several Gulf countries.

In 2011, the Food and Drug Administration in the Philippines banned grocery manufacturing company Kraft's food and dip products which contained poppy seeds.