Consumers could face higher food prices as extreme weather caused by climate change affects major crops worldwide, according to a new Oxfam report.

The charity claims the full impact of climate change on future food prices is being underestimated and warns consumers will become more vulnerable to events such as the current US drought as dependence on exports of wheat and maize increases.

The report, Extreme Weather, Extreme Prices, says a US drought in 2030 could raise the price of maize by as much as 140% over and above the average price of food, which is already likely to be double today's prices.

Drought and flooding in southern Africa could increase the consumer price of maize and other coarse grains by as much as 120% by 2030, the reports says, while nationwide drought in India or extensive flooding across Southeast Asia could see the world market price of rice increase by 22%.

The report warns such rises would affect UK consumers, who are already facing high food prices without the full weight of extreme weather events and climate change.