Birds Eye and Walkers have joined Typhoo and Unilever in asking supermarkets for more money following the drop in the value of the pound.

In the latest spat between suppliers and retailers, Birds Eye and Walkers are asking supermarkets for price rises of up to 12%.

Supplies of Unilever products started to run low after the Marmite-owner and Typhoo went to war with Tesco over prices last month.

The disputes have been fuelled by the 14.5% drop in the value of the pound against the euro and 18% against the dollar since the UK voted to leave the European Union.

Birds Eye, owned by New-York-listed Nomad Foods, told The Guardian its sterling costs had risen because many of its raw materials were priced in dollars.

If it does not get the 12% increase it has requested, it may shrink pack sizes to help offset the costs – cutting the number of fish fingers in a packet from 12 to 10, for example.

Birds Eye UK and Ireland managing director Wayne Hudson said: “Increasing costs is not a decision we take lightly, and the last time it was necessary to raise costs was in 2012.

“As such, we have been in open and collaborative conversations with the retailers for some time now and are working closely with them to minimise any impact on our customers.”

Imported ingredients

Leicester-based Walkers, which is owned by PepsiCo, is understood to be seeking price rises of between 5% and 10%, taking a 32g bag of crisps from 50p to 55p.

A Walkers spokesperson said: “Whilst our potatoes are British, we import a number of different ingredients and materials to produce a finished packet of Walkers crisps.

“Fluctuating foreign exchange rates, supply pressure on key ingredients and the weakened value of the pound are impacting the import cost of some of our materials and affecting the price of material costs based on commodities that are traded in foreign currencies.”

UK supermarkets are resisting price rises in order to remain competitive against the discounters.

However, according to analysis by the Guardian and, the price of a basket of 20 Unilever products has risen by an average of 5.7% across the UK’s major supermarkets since the Brexit vote.