Fitch Ratings said in a new report that Hong Kong banks' trade finance services will continue to grow steadily and become more dependent on the Chinese mainland.

In addition, banks will continue to expand their non-trade related China businesses as the two economies further integrate and domestic lending remains muted.

"This could increase banks' risk profiles and pressure ratings, unless managed prudently," the rating agency said.

Fitch expects Hong Kong banks' trade-related exposure to grow at a healthy pace of about 20 percent a year in 2013.

Expansion into the mainland appeals to Hong Kong banks due to increasing domestic competition. Given their franchises in China and international connectivity, the subsidiaries of Chinese banks and large global banks are best positioned to capture growth in this market.

The trade finance boom from 2010 to 2011, triggered by interest and foreign exchange rate arbitrage transactions, is unlikely to continue, Fitch said.

"Rather, growth is likely to be underpinned by genuine trade volumes as expectations for the RMB to appreciate wanes and lending restrictions for Chinese banks ease," the agency said.