The typical two-year fixed mortgage has fallen to 2.11 per cent, a low not seen since October 2017, according to data analysis by Moneyfacts.
Lenders have reduced the number of mortgage products available since the outbreak put the country on lockdown, with many pulling deals at higher loan to values (LTV), which typically have higher rates.
This is likely to account for a significant part of the average rate fall.
However, over the past week a number of lenders have brought back higher LTV mortgages, including Halifax and Nationwide which both reintroduced lending back up to 85 per cent LTV.
The two-year average rate has fallen from 2.28 per cent on 3 April, and 2.39 per cent on 24 March.
This time a year ago the rate was at 2.48 per cent.
Eleanor Williams, spokeswoman at Moneyfacts, said: “The number of available mortgage products, and also therefore choice for borrowers, has reduced over recent weeks in response to the ongoing Covid-19 pandemic and lockdown restrictions, as lenders acclimatise and adapt to the ever-changing circumstances.
“However, also experiencing a reduction are the average rates available for two- and five-year fixed deals. This may well in part be due to the fact that many of the mortgage products which have been withdrawn recently were those which offered higher loan-to-value ratios, and where risk, and therefore rates, are traditionally higher
“This recent removal of some higher loan-to-value mortgage may be a temporary measure, while mortgage providers reassess risk in this area of the market.
“Indeed, we are beginning to see positive signs that providers are beginning to relaunch products, with some of the larger banks reintroducing products in the 80 per cent and even 85 per cent loan-to-value brackets this week.”