CENTRAL Asia Capital, a Hongkong deposit-taking company, has joined with Bank of China to open a branch in Fuzhou. The 50-50 joint-venture, known as Fujian Asia Bank, will be Central Asia's first venture in China. ''Fuzhou is only our stepping stone. We plan to set up additional offices in other cities in Fujian, and later in other provinces,'' said Mr Joseph Lau Kin-man, assistant general manager. However, Mr Lau added that the banking system in China would have to be further reformed. The branch will begin operation in April, and employ up to 50 staff. It will focus on financing foreign joint-venture projects in Fuzhou, where Taiwan provides 40 per cent of the foreign funds. Fuzhou, the capital of Fujian province, was one of seven cities permitted by Beijing in May to grant full licences to foreign banks. Two other foreign banks - Chiyu Banking and Xiamen International Bank - recently opened in the city.