A Bank of China (BOC) spokesman has confirmed the second biggest Chinese lender has "no concrete timetable" for a planned listing on China's mainland stock exchange, following its recent share offering in Hong Kong.

"BOC will materialize an A-share market listing as soon as possible," Wang Zhaowen told a Xinhua-run economic newspaper, in reference to China's renminbi-denominated shares trading market for domestic investors.

But he quashed rumors in some media reports that the bank would go public on the mainland market as early as next month.

"We still have a lot of work to do," he said, "though preparations for listings in Hong Kong and the mainland are continuing simultaneously."

The BOC's 9.7 billion U.S. dollars initial public offering in Hong Kong, the world's biggest in six years, has drawn keen interest from stock market investors hoping to buy into China's rapid economic growth, despite recent turmoil in Asian stock markets, including Hong Kong.

With shares representing a 10.5 percent stake in the bank priced at 2.95 Hong Kong dollars (38 U.S. cents) each, BOC has an initial market capitalization of about 750 billion Hong Kong dollars (96 billion U.S. dollars). That ranks between Germany's Deutsche Bank AG and Switzerland's UBS AG but well behind U.S. banks Citigroup Inc. and Bank of America Corp.

The BOC's shares begin trading on June 1 in Hong Kong.