BEIJING -- China Merchants Bank Co Ltd, the country's sixth-largest lender by assets, said on Wednesday its net profit in 2011 surged 40.2 percent year-on-year to reach 36.13 billion yuan ($5.74 billion) thanks to rapid growth in interest margins and fee income.

Net interest income, or revenue from borrowers minus interest paid to depositors, increased 33.69 percent from previous year to 76.31 billion yuan in 2011, according to the annual report the bank filed with the Shanghai Stock Exchange.

Commissions and income from services fees, another major contributor to the bank's profit growth, went up 38.8 percent year-on-year to reach 19.85 billion yuan.

The capital adequacy ratio (CAR) of the bank stood at 11.53 percent last year, compared with 11.47 percent in 2010.

The bank's non-performing loans outstanding dropped by 513 million yuan to reach 9.17 billion yuan, with non-performing loan ratio dipping slightly to 0.56 percent from 0.68 percent in 2010.

The bank's total assets increased 16.34 percent year-on-year to reach 2.79 trillion yuan last year, according to the report.