You may have trouble finding crumpets in supermarkets as Warburton's suffers the effects of a carbon dioxide shortage.

One of the UK's biggest bread makers says it has ended production at two out of four of its plants because they have run out of CO2, which they use to package the product.

The shortage affects the Warburton's London and Burnley plants, and there is not a frequent supply at its Stockton site.

"As a result of the ongoing CO2 shortage, we are producing nowhere near the 1.5 million packs of crumpets we usually make each week," says Tearmh Taylor, corporate and consumer affairs manager at Warburtons.

"This will remain the case until the CO2 supply returns to normal. But, rest assured we are working really hard to keep our products on Britain's shelves."


:: What is the CO2 shortage about?

The low supplies are due to a longer than usual break in production of ammonia, one of the key sources of Europe's food grade CO2.

Carbon dioxide is widely used in "modified atmosphere packaging".

It is part of a gas mixture which is used to remove oxygen from food packaging to prolong the shelf life and keep food looking fresh.

The CO2 cris has also hit the brewing industry and some pig processing plants.