The bank received 10,000 phone calls in four days from interested parties, and booked 5,000 appointments within three hours of the scheme going live.
RBS said that the average applicant for its 95% mortgages, which will be backed by the government scheme, was 32 years old and seeking a joint mortgage with a partner.
The youngest applicant was 19 years old and the oldest 42.
Lloyd Cochrane, head of mortgages at RBS and its NatWest subsidiary said:
“From the moment we launched our Help to Buy mortgage products, the response we’ve had from customers has been fantastic. “We knew there was pent up demand, from speaking to customers we knew there was a frustration and a desire for these products.”
He added: “We expect demand for our 95% mortgage to continue, and with appointments for next week already filling up fast, from Tuesday over 740 of our branches will be open longer to make sure we continue to help as many customers as we can.”
RBS is offering a two-year fixed rate charged at 4.99% and a five-year fixed rate charged at 5.49%. Both are fee-free and available throughout the UK. Other lenders already offer 95% mortgages not linked to the government scheme, some priced more cheaply, but they are few and far between and sometimes come with regional restrictions.
Halifax is so far the only other mainstream bank to have started offering Help to Buy 2 mortgages but Santander, HSBC and Barclays have all confirmed they will be taking part.
Smaller banks Aldermore, OneSavings Bank and Virgin Money are among lenders planning to launch Help to Buy-backed mortgages in 2014.
RBS has said that it plans to provide a total of 25,500 Help to Buy-linked mortgages via RBS and NatWest.
Speaking at last week’s launch, Cochrane said it may only take “two to three weeks” for the first person to move in with a Government-backed mortgage.