Some of the biggest confectionery firms are shrinking their chocolate bars to protect profits.

Companies such as Nestle and Birmingham-based Cadburys have reduced the size of some of their most popular brands.

Yet at the same time prices of bars will actually increase to shelter profits from the rise in VAT, looming in January. Family favourites such as Dairy Milk bars will lose a couple of chunks in February, while Maltesers will drop their weight per bag from 140g to 120g.

Meanwhile, Poundland will cut its Toblerones by one triangle, although chief executive Jim McCarthy says the move is being taken so that the price of a Toblerone bar remains at £1.

A spokesman for Cadbury said pack sizes were being varied to provide consumers with more choice. “We have taken the decision to increase prices because of economic factors such as ingredient costs.”

Mintel analyst David Jago said the first wave of changes in confectionary value went largely unnoticed. Changes in the sizes of bars such as Mars and Twix were not obvious to most consumers, but now that companies are changing the price of bars as well, people are seeing a change.

Jago said the changes are a tactic being used by confectionary companies to keep profit margins stable when VAT is expected to rise and the price of sugar and cocoa are also increasing.

He also said manufacturers had been asked to alter the size of packs to help tackle the obesity epidemic.

The cost of chocolate has been rising since 2007 when cocoa prices hit a 33-year high over £2700 a tonne.

Customers are already seeing price rises at newsagents.

Cadburys and Nestle have boosted recommended retail prices of Kit Kat, Yorkie, Wispa and Dairy Milk by a noticeable seven per cent. A Nestle spokesman said the company ‘occasionally’ made changes to prices due to a change in packaging.