More than half of mortgage holders have no plan in place for how they will cope with interest rate rises, according to research from a Government-backed body.

Some 56% of mortgage holders surveyed for the Money Advice Service (MAS) admit to having done nothing so far to prepare for the prospect of their home loan repayments becoming more expensive after the Bank of England base rate moves off its historic low.

This is despite almost one in five (19%) of the 3,000 UK mortgage holders surveyed saying that they will "really struggle" to cover any increase to their monthly payments.

Banks and building societies are warning homeowners to start planning now for the impact of increased mortgage costs on their budgets.

The MAS found that young mortgage holders are both more likely to be unaware that rates are likely to rise at all, and to have been financially stretched when they took out their home loan in the first place.

One in 12 (8%) of people across all ages said they were not aware that rate rises are expected to be on the horizon, rising to one in six (16%) mortgage holders aged under 35.

More than two-thirds (69%) of homeowners generally said their finances were stretched when they took out their mortgage, increasing to over three-quarters (77%) of under-35s.

The expected rise in interest rates will be a new experience for many homeowners. According to industry estimates, around one million home owners have never experienced an interest rate increase, having climbed on to their first rung of the property ladder after the base rate fell to its rock bottom level of 0.5% in 2009.

How quickly a borrower feels the impact will depend on what type of mortgage they have.

Around nine in 10 new mortgages being taken out by first-time buyers and existing homeowners are fixed-rate products, which cushion the borrower from any immediate impact of the base rate rising. Meanwhile, around one in 20 new mortgages are trackers, which are directly linked to the base rate. Lenders also offer standard variable rate (SVR) mortgages, which is a rate that they set themselves.

Almost one in three (28%) of current mortgage holders do not even know what their current mortgage rate is and one in 33 (3%) are unaware exactly how much money currently goes out of their account every month to cover their mortgage, the MAS found.

Nick Hill, a money expert at the MAS, said that even for those on a fixed rate "their deal will come to an end sooner or later".

He continued: "Those who purchased their first property in the last five years will have only ever known historically low interest rates, but less than 10 years ago the interest rate set by the Bank of England was 5% higher than today."

Some brokers have pointed out that the current mortgage market presents a particularly good window of opportunity for people to take out a new deal as they start to plan ahead.

A mortgage price war has broken out in recent weeks with a string of lenders slashing their rates. Experts have put this down in part to falling swap rates, which lenders also use to price their loans, as well as lenders looking to meet end-of-year targets.

The MAS, an independent body set up by the Government to offer free money tips, also found that nearly half (47%) of mortgage holders would find it hard to meet a £150-a-month increase in their payments.

However, the Council of Mortgage Lenders (CML) said that a £150 increase would equate to a two percentage point increase to the average mortgage, which is something the markets think is unlikely to happen until around 2018, by which time earnings are also expected to have increased.

The CML said its own research has shown that for most people, the widely expected scenario of gradual rate increases is likely to be manageable.

In the short term, a 0.25% increase would add around £16 a month on to an average mortgage, it said.

The CML said that as a general checklist, it makes sense for all mortgage holders to remind themselves what rate they are on, whether it is fixed or variable, and when it expires.

They can also use a new tool placed on the Money Advice Service's website to work out what rate rises of different sizes would mean for them.

If someone is worried that they are going to struggle, they should consider whether there are other areas of their spending that they can reduce as well as speaking to their lender.

CML head of external affairs Sue Anderson said: " Although we don't know when rates will rise, the monetary authorities have previously flagged that rises will be finely calibrated, so large sudden shocks are unlikely.

"By planning ahead now, mortgage holders can get a clear picture of what a rate rise would mean for their own repayments.

"Taking steps in advance to work out what the effect on your payments might be, and planning ahead, will mean that most borrowers will be able to cope by careful budgeting. On an average mortgage of around £120,000, a quarter point rise would typically add around £16 to the monthly payment."

:: Mortgage holders can find out more about how they personally could be impacted by rising interest rates by visiting moneyadviceservice.org.uk/interest-rates-rise.