And UK health insurance costs are anticipated to grow by the largest figure in five years in 2016, analysts say.

They will jump by 6.5% this year, according to Willis Towers Watson’s 2016 Global Medical Trends report.

Researchers said that high claim volumes meant that health insurance costs have been increasing year-on-year at one of the highest rates in Europe.

Jeremy Hill, director in Willis Towers Watson’s Global Services and Solutions business, said: “In the last ten years, the cost of health insurance in the UK has almost doubled putting enormous pressure on budgets.”

“The cost of health insurance continues to rise ahead of inflation almost everywhere in the world. While the last five years have seen relative stability in UK cost increases, the trend is starting to creep upwards and 2016 is predicted to surpass last year’s increase - for the third year in a row.”

According to the report, the main causes of high price increases in UK health insurance are: an ageing workforce more likely to claim on their insurance; continuing delays in NHS treatment driving individuals to seek a private-sector solution; and the increasing availability and use of costly medical treatments.

Within Europe, among very varied health systems, the UK experience surpassed that of France and Spain, which are expected to have modest increases of 3.5% and 1.2% respectively. Italy (0.8%), Portugal (2.1%), Greece (4.7%) and Belgium (5%) are also anticipated to experience lower health insurance inflation this year, as they have in each of the past three years.

According to the report, the UK did not suffer the largest price hikes in Europe. Nordic countries such as Norway (10%) and Sweden (8%) will experience higher cost increases, and Russia tops the European table for the second year running with 15% cost increases.

Globally, the average health insurance price increase for 2016 is estimated to be 9.1%, up from 8% last year and 7.5% in 2014, so European cost increases are relatively modest compared to other continents. In the Middle East and Africa, health insurance inflation rose from 10.3% in 2014 to 12.6% in 2015, and is expected to continue to rise.

Mr Hill said: “Health insurance remains a key employee benefit in the UK, but the effect of aging workforces, costly and complex treatments, and technological advancements is that health insurance inflation in the UK is higher than in most of Europe.

“Employers continue to keep health costs under review, with many looking at cost-sharing mechanisms to contain cost, as well as looking at health and wellbeing approaches to improve the underlying health of employees.

“At the same time, UK providers are attempting to curtail these annual price increases. As both the provider market and insurers have consolidated, insurers are using their size to leverage more favourable pricing agreements with key hospital groups and service providers. In addition, some smaller insurers are forming independent healthcare purchasing alliances to procure competitively priced hospital treatment for their members.”

The report shows that, during the last five years, the annual increase in the price of UK health insurance has been between 5.1% and 6.4%, a period of relative stability compared to the period from 2007 to 2011, when UK prices spiked by between 8% and 9.6% each year.

But the cost increases have been increasing steadily in the last three years, from 5.1% in 2013 to 6.4% last year and predicted to hit 6.5% this year.