COLD homes have been blamed for the number of winter deaths rising to a 15-year high.

Nursing leaders and campaigners have called on politicians to "end the scourge" of badly insulated and hard-to-heat homes after the data showed the spike in deaths.

Official figures from the National Records of Scotland show there were 22,011 deaths registered in the four months between December 2014 and March 2015. The number was up from 18,675 the previous season and the highest since the winter of 1999/00, when there was a flu outbreak.

Statisticians said the mortality rates for the season were "unusually high" for the 21st century, although there was relatively low level of flu, traditionally the main killer during colder weather.

But Theresa Fyffe the Royal College of Nursing (RCN) Scotland’s director, said that poorly-heated homes exacerbated winter mortality rates and that more should be done to help people keep warm.

She said: “It's indefensible that cold, hard-to-heat homes continue to leave the most vulnerable in our society at the mercy of cold weather each winter.

"Nurses are on the frontline of caring for patients and are all too familiar with the stories behind these winter mortality statistics.

"Ending cold homes and cutting fuel bills through improving the energy efficiency of Scotland’s homes should be a priority for political parties coming in to next year’s Scottish Parliament election.”

Last winter saw hospitals come under increasing pressure, leading to talk of a crisis with hundreds of pre-planned operations called off at short notice due to a spike in urgent cases while 1,200 beds a day were unavailable due to delayed discharges in December.

Tim Ellis, chief executive of the National Records of Scotland, said there was no single cause behind the spike last year and Scotland's chief medical officer Catherine Calderwood said the deaths were caused by a number of conditions including respiratory and circulatory diseases.

But Age Scotland’s Greg McCracken said that many elderly people struggled to heat their homes, adding: “The poor condition of Scotland's existing housing stock means much of the energy which older people use trying to stay warm will be lost, something many can ill-afford.

"That's why a comprehensive and long-term approach to ridding Scotland of cold and draughty homes is critical if we are to ensure figures like these are consigned to the history books."

WWF Scotland director Lang Banks said that lessons could be learned from Scandinavian countries, which cope better with cold winters.

He said: “Their better quality housing means that they have less of a problem with increased winter mortality.

"Improving the energy efficiency of Scotland’s homes would make a significant contribution to reducing the number of vulnerable people who die each winter from the effects of cold homes. Insulating all homes to a ‘C’ standard would also create up to 9,000 jobs a year, cut fuel bills and help tackle climate emissions.

"We urge all the political parties to commit to eliminating the scourge of cold, energy-wasting, hard-to-heat homes in Scotland.”

Mr Ellis said the long-term trend since 1951/52 had "clearly" been downward.

"Despite the latest winter's unusually high figure, the five-year moving average is at its second lowest ever level," he said.

"Very few [deaths] are caused by hypothermia and only a small proportion by influenza. The underlying causes of most of the additional deaths include respiratory and circulatory diseases, dementia, and Parkinson's, Alzheimer's and other degenerative diseases."

Dr Calderwood urged older people and those with underlying health conditions to take up free flu vaccinations.

She said: "We have heard from NHS health boards of more, sicker, patients arriving at hospital, which possibly reflects the growing number of elderly people living in Scotland with multiple health problems.

"While in many cases of winter mortality influenza will not be the main cause of death, it can aggravate underlying long-term conditions, which may have had a significant impact on the sick and elderly last winter.

"This is why it is crucial that those with underlying health conditions, those who are pregnant or are older than 65 receive their free flu vaccination."

A spokesman for the Scottish Government said: “We recognise that living in a cold, damp home may impact on some physical conditions as well as mental wellbeing.

"That is why we have allocated over half a billion pounds since 2009 on a raft of Fuel Poverty and Energy Efficiency programmes and this year a record budget of £119 million is being made available for fuel poverty and energy efficiency.

“This government remains committed to tackling fuel poverty and our spending on domestic energy efficiency has already made hundreds of thousands of homes warmer and cheaper to heat and has helped to mitigate the rise in fuel poverty.”