In November £2.1bn of mortgages were approved in November, up 13% on November 2010.
Gross mortgage lending by mutuals for the first 11 months of 2011 increased 16% to £21.5bn compared to the same period in 2010.
In the first 11 months of 2011 there was also a 17% rise in mortgage approvals at £21.3bn compared to the same period in 2010.
Adrian Coles, director general of the BSA, said: “Mutuals have shown their resilience in the face of tough market conditions over the past year and have continued to see their new mortgage lending increase.
“Mutuals lent 16% more from January to November 2011 compared to the same period in 2010, whilst lending across the mortgage market as a whole has remained broadly flat.
“The New Year has seen some excellent mortgage products go on sale from mutuals with a return to some offering higher loan to value mortgages. These are encouraging trends against rather discouraging developments in the wider economy.”
