Prices rose after the US Fed's chair warned tariffs could hit economic growth and fuel inflation.

The firms said operating expenses have risen "due to recent changes in global trade rules and tariffs".

People coming into Great Britain can no longer bring cured meats or cheese from the EU following an outbreak of foot-and-mouth disease.

Jerome Powell, chair of the Federal Reserve, said Donald Trump's new import taxes were larger than expected.

The Geneva-based institution says American tariffs will send international trade into reverse.