Many supermarket items are getting smaller as prices remain the same - or even increase, a consumer group has warned.

In its latest round-up of shrinking groceries, Which? listed toilet roll, chocolate biscuits, orange juice and antibacterial wipes, among others.

A standard Andrex pack of four toilet rolls has reduced from 240 to 221 sheets, 8pc less, yet the price has remained around the £2 mark, the watchdog found.

McVitie's Digestives dark chocolate biscuits decreased from 332g to 300g, a 10pc reduction, yet were sold in Tesco for £1.59 before they shrank and increased to £1.69 afterwards.

Tropicana Creations Pure Premium Orange & Raspberry juice decreased from 1 litre to 850ml, a 15pc reduction, yet remained the same price of £2.48 in Asda.

Dettol Power and Pure Bathroom Wipes decreased from 36 to 32 wipes, an 11pc reduction, but remained at £2 in Tesco and increased to £2.03 at Ocado.

Percol Fairtrade Guatemala Coffee decreased from 227g to 200g, a 12pc reduction, and although it dropped in price from £3.90 in Sainsbury's and Waitrose to £3.65 and £3.75 respectively, both amounts were more per 100g than the original.

Most brands, responding to the Which? research, said it was up to supermarkets to set the price, but they would not disclose if they had charged the stores a lower wholesale price.

A poll by Which? found 78pc of its members do not think it is right if consumers are not told when products drop in size but remain at the original price.

Which? editor Richard Headland said: 'Shrinking products can be a sneaky way of increasing prices. We want manufacturers and supermarkets to be upfront about shrinking products so consumers aren't misled.'