This compared to just over £1bn of gross mortgage lending in January 2010.
The BSA figures figures revealed that mutuals approved £1.1bn-worth of loans in January, up 37% on £820m in January 2010.
Net lending by mutuals in January 2011 was -£526 million compared -£838 million in January 2010.
Adrian Coles, director-general of the BSA, said: “Mortgage lending by mutuals in January was up year on year, although the comparable figure for January last year was depressed, as it followed the termination of the last government’s Stamp Duty holiday that ceased at the end of 2009.
“On a seasonally adjusted basis, mutuals’ mortgage lending and approvals figures for January were broadly similar to the averages over the preceding six months.”
Meanwhile, savings balances held by mutuals fell £424m in January 2011 compared to a decrease of £467m for the same period last year. Net withdrawals amounted to £697m in January compared to £741m last year.