An iconic Scottish product has disappeared from shops after a packaging issue affected supply.

Scottish Plain loaves by Mothers Pride have not been seen on bread shelves for about two weeks.

Suppliers have blamed a “manufacturing issue” at Hovis, which makes the 90-year-old product.

A spokesperson apologised for the shortage but said the popular loaf would be back on shelves in early June.

Scottish Plain has a well-fired top and bottom but no crust at the sides due to the batch baking process.

It was one of the best-selling white breads in the 1970s and 80s but the batch plant in Glasgow which makes Scottish Plain is now the last in the UK.

One shopper said: “It’s the same in all the shops, it’s not just here.

“Even if you go further afield there’s nothing there and we don’t know when it’s coming back.”

It is thought the shortage is due to a packaging issue which means slices of bread are sticking to the wax-coated wrapping paper.

A plain loaf is made in a large baking tray, making it different from a pan loaf which is baked in an individual tray so that a crust forms on all sides.

The two types of bread were immortalised in the Jeely piece song – a Scots folk song written in the 1960s – in the line: “If it’s butter, cheese or jeely, if the bread is plain or pan”.

The loaf has been wrapped in wax-coated paper since it was first sold in 1936, but it will now transition to a standard bread bag.

A spokesperson for Hovis said: “We are proud to have baked and supplied Mothers Pride Scottish Plain to the highest standard for many years and apologise for the current temporary disruption to supply.

“We want to reassure customers that Mothers Pride Scottish Plain will be back on shelves early in June.”