The lender carried out £5.6bn of gross lending in the first three months of 2012, compared with £4.2bn in the same period last year.
Its net lending in the first three months of the year was £200m, compared to – £600m in the first three months of 2011.
In its results the lender says it has tightened its risk appetite in the retail mortgage market and is originating less business for higher LTV deals and interest-only mortgages.
As a result it expects its mortgage stock to contract over the year.
Its results say: “In March 2012, Santander UK announced it was tightening its lending criteria on interest-only mortgages as part of a range of actions to further improve the credit quality and profitability of the mortgage book.
“Notwithstanding this, mortgage gross lending in the first quarter of 2011 was £5.6bn, equivalent to a market share of 17.6%.”
The results add: “Mortgages and savings continued to be a core component of the retail offering, through both direct and intermediary channels.”
Overall Santander Group made a profit after tax of €1.6bn, down 24% mainly due to increased provisions for non performing loans.
Pre-provision profits were €6.2bn and up 9%.
Its UK profit before tax was £347m, down around 40% from Q1 2011 when it was £590m.