Tesco has increased the price of its cheapest bottled water and fizzy drinks as sales surge in the scorching weather.

Tesco upped the price of its two-litre Everyday Value water and cola 41% to 24p last week. The price increases make the products more expensive than equivalents at rivals Asda, Sainsbury’s and Morrisons.

The price rises came amid fears of bottled water shortages as temperatures soared above 30 degrees in some parts of the country.

Grocers are typically recording a doubling in water sales through the hot spell, according to The Guardian.

Tesco said its price increase last week reflected the cost of production, which it kept as low as possible. A spokesman said: “We think four bottles of filtered water, cola or lemonade for less than a pound is still very good value.”

But retail observers said Tesco’s customers were unlikely to agree.

Shore Capital analyst Clive Black said: “Tesco has probably jacked the price up because it’s hot and product is going out the door. It’s taken a commercial view but it’s not necessarily one all its punters will like.”

He said the price hike suggested that either Tesco was trying to ration drinks because supplies were tough to come by or it wanted to increase its profits.

Neil Saunders, managing director of retail consultancy Conlumino, said: “I find it quite surprising that Tesco has moved its price when its competitors haven’t. It will not only get angry customers, if they notice, but this makes Tesco less competitive when there is a price war on in grocery.”