Bank of China, one of China's "Big Four" lenders, said Thursday its 2011 net profit rose 18.93 percent despite a "complex and severe business environment".

The bank said profit attributable to equity holders was 124.18 billion yuan ($19.69 billion), compared with 104.42 billion yuan in 2010.

China's fourth largest bank by assets said operating income in the 12 months to December 31 last year was 328.3 billion yuan. Its capital adequacy ratio rose to 12.97 percent compared with 12.58 percent a year earlier.

"International trade lost steam and international financial markets fluctuated drastically," chairman Xiao Gang said in a statement to the Hong Kong stock exchange.

"China continued to transform its development model and the national economy maintained its smooth and rapid growth.

"However, there are still some obvious problems arising from unbalanced, uncoordinated and unsustainable economic development, even if Chinas long-term prospects are promising."

The lender released its results after the market had closed with shares down 1.91 percent at HK$3.08. The overall Hang Seng index was 1.32 percent weaker.

Xiao said the bank had achieved "significant breakthroughs" in infrastructure and information technology, allowing improved online banking.

The lender planned to "build a new smart-bank model driven by technological innovation" in 2012, he said.

Bank of China suspended trading of foreign exchange swaps with some European banks in September last year, indicating it was concerned about their credit worthiness amid the eurozone debt crisis.

China last month trimmed the reserve requirement for all commercial banks nationwide by 0.50 percentage points -- the second cut since December last year -- to ease restrictions on lending and boost slowing economic growth.

China is expected to further ease monetary policy by cutting reserve requirements as growth slows to help prevent a "hard landing" for the world's second largest economy, analysts say.

Economic growth in China hit 9.2 percent last year, slowing from a blistering 10.4 percent in 2010, as global turbulence and efforts to tame high inflation put the brakes on growth.

Earlier this month, Chinese Premier Wen Jiabao cut the country's growth target for 2012 to 7.5 percent, down from an eight percent target last year.

China's central bank chief said last week conditions were ripe for Beijing to liberalise interest rates, a move analysts said would boost domestic demand as the nation's exports are hit by overseas turmoil.