Increasing numbers of FTBs were also forced to pay stamp duty - 58 per cent in April 2007 up from 51 per cent over the same period last year.
"Month on month we see affordability constraints for first-time buyers worsening. And with the impact of May's interest rate rise still to be felt, many borrowers face higher costs in the coming months," the CML's director general Michael Coogan said.
"The vast majority of borrowers will be able to absorb higher mortgage payments. But with two million fixed-rate loans coming to an end over the next year and a half, many borrowers should anticipate that their mortgage costs are likely to rise and should be planning ahead."
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