The US-based maker Mondelez International blamed a rising cost of ingredients for its decision to increase the gap between the chocolate peaks.
However, the change appears to have been made only to bars sold in the UK - prompting speculation that Britain’s Brexit vote is to blame.
Some consumers took to social media to call the bigger spaces “stupid”.
The company said on Facebook it had to make a decision between changing the look of the bars or raising the price.
The move has resulted in the weight of the 400g bars being reduced to 360g and the 170g bars to 150g, while the size of the packaging has remained the same.
It said: “We chose to change the shape to keep the product affordable for our customers.”
On Facebook, consumer Lee Yarker said: “Fair enough reducing the weight of the bar, but why the big gap in between segments? Looks stupid imo [sic], could have just made the bar shorter and kept the original design.”
The company later denied the change was made as a result of the Brexit vote.
A spokeswoman admitted the foreign exchange rate was currently “not favourable”, but said: “This change wasn’t done as a result of Brexit.
“Like many other companies, we are experiencing higher costs for numerous ingredients. We carry these costs for as long as possible, but to ensure Toblerone remains on-shelf, is affordable and retains the triangular shape, we have had to reduce the weight of just two of our bars in the UK, from the wider range of available Toblerone products.”
Walkers and Birds Eye have said will raise the prices of some items following the drop in the UK exchange rate.
Last month, Unilever raised prices in Britain to compensate for the fall in the pound.