UK charities have united to call on the government to do more to tackle rising energy prices.

The group, of 27 charities, wrote a letter to the Prime Minister and the Chancellor on January 14, calling for urgent action to tackle the energy bill crisis and emergency funding to support the most vulnerable.

Charities joining the call included Age UK, WWF, Green Alliance, Faith for the Climate, Tearfund and Greenpeace.

As the Government considers steps to help those facing rising bills, the charities told the Prime Minister that a cut in support for making homes energy efficient after the last surge in energy bills in 2013 left households far more vulnerable to surging gas prices.

Without government action, the energy price cap could be increased by £600 in April, driven by the surging price of gas on the international markets, taking an average energy bill to around £2,000, they said.

The charities estimated fuel poverty could increase by 50%, from 4 to 6 million households across the UK, prompting fears this will lead to households choosing between heating and eating, an increase in the number of people dying in cold homes and a greater burden on the NHS.

William Baker, of Solutions to Tackle Energy Poverty, said: “The Energy Company Obligation is central to the Government’s legal duty to abolish fuel poverty by 2030.

"Scrapping the programme would show the Government does not take its statutory responsibilities seriously. It would condemn many fuel poor households to unaffordable fuel bills, ill health and in the worst cases death as a result of living in dangerously cold, unhealthy homes.

"The government must take urgent action to address the current crisis of rocketing fuel bills and expand its programmes to upgrade the insulation and heating systems of our notoriously leaky homes so that we are less dependent on volatile gas markets.”

Dan Paskins, director of UK Impact at Save the Children, said: "The cost of living crisis, fuelled by soaring energy prices, is totally unsustainable and is hitting the lowest income families the hardest.

"Parents we work with tell us that they’re struggling to meet basic needs, leaving them having to make impossible choices between heating their homes and buying clothes for their children. And children are paying the price.

"Children deserve a fair and green future, and need a concrete plan from the UK Government that tackles both the cost-of-living and climate crises."

And Dr Doug Parr, policy director at Greenpeace UK, said: "The twin imperatives of a gas price crisis and the climate crisis mean we need to get off fossil fuels as fast as we can whilst protecting people on low incomes.

"That means we need to see short-term support for fuel poor families and long term support for energy efficiency and cheap renewables.

"A windfall tax on oil and gas companies would be a fair way to help finance the transition as we exit fossil fuel production in line with advice from leading experts at the International Energy Agency."

A spokesperson for the End Fuel Poverty Coalition, which was also a signatory to the letter, added: "After years of tireless campaigning by health, anti-poverty and environmental charities, trade unions and researchers, politicians are finally waking up to the tragedy of fuel poverty in the country.

"Fuel poverty is a public health and social crisis but can only be solved by economic measures and the Government must do everything possible to help people in crisis now while investing in energy efficiency programmes to fix the long-term problems."

The charities are also calling for emergency support for the most vulnerable, and recommend expanding the Warm Homes Discount and giving those on universal credit and providing a one-off payment to those eligible for Cold Weather Payments.