First-time buyers are the most exposed group in the housing market as mortgage withdrawals and rising borrowing costs increase pressure on those most reliant on home loans.

Data from reallymoving shows that 90.5% of first-time buyers used a mortgage to buy a home over the past six months, the highest share of any buyer group. That compares with 87% of upsizers, 82.1% of investors and 40.5% of downsizers.

In March, the proportion of first-time buyers using a mortgage rose to 92.6%, which reallymoving said was the highest level since October 2013. The figures suggest first-time buyers remain particularly vulnerable to any sudden change in mortgage pricing or product availability.

The pressure is not confined to new entrants to the market. Reallymoving said the wider housing market is also feeling the effect of disruption in lending conditions, with large shares of upsizers and investors also dependent on borrowing to complete purchases.

London appears to be the most exposed region. Reallymoving’s figures show that 87.4% of buyers in the capital used a mortgage, the highest level of any region in the UK, while the North East recorded the lowest level at 77.3%.

The capital also has the largest concentration of first-time buyers, who account for 63% of all buyers in London. That leaves the market particularly sensitive to rate rises and lender withdrawals.

According to the release, mortgage reliance among first-time buyers exceeded 90% in every region except the North East, Wales and Yorkshire & Humber, where it was only slightly lower.

Rob Houghton, founder and chief executive of reallymoving, said: “Expectations that borrowing would become cheaper this year have been turned on their head. Inflation, which was unchanged in February at 3%, is now on course to shoot back up and as a result we’re likely to see the base rate rise this year rather than fall.

“Lenders are spooked and amid the uncertainty we’re seeing hundreds of products being pulled, with rates rising across the board. Anyone hoping to buy this year will be concerned, particularly first-time buyers who are most heavily dependent on mortgages, and existing homeowners with deals due to expire in the next few months.

“The focus will be on securing a deal as quickly as possible before costs rise further, and for those buyers with a mortgage offer in place, the rush is on to find a property and exchange before it expires.”