Polish chemical firm Grupa Azoty's Pulawy unit is producing carbon dioxide at less than a third of nominal capacity as high natural gas prices hit profitability, a group spokesperson told Reuters.

Carbon dioxide (CO2) is a byproduct of ammonia output, and soaring gas prices are making profitable production of ammonia and nitrogen fertilisers impossible, she said.

The company said on Tuesday that due to higher gas prices Pulawy was cutting ammonia production to about 10% of capacity, and temporarily halting output of nitrogen fertilisers and some other products.

"At Grupa Azoty Pulawy 30% of nominal CO2 production volume is being maintained," the spokesperson added in an e-mail on Friday.

A CO2 shortage is already putting pressure on some European countries' food sectors. The food industry uses carbon dioxide for, among other things, cooling products during transportation, stunning poultry and pigs before slaughter, and putting fizz in drinks.

On Thursday Danish brewery Carlsberg's Polish unit said it might have to stop production due to a shortage of CO2 supplies, which could also hit the wider food industry in Poland.

FACTBOX-Food industry in some parts of Europe under pressure as CO2 runs short.