BEIJING -- China will allow four more overseas companies to move money into the country's capital account in May, as China is determined to speed up the yuan's convertibility.

In the Qualified Foreign Institutional Investors (QFII) program, four companies including Brunei Investment Agency were added to the list, bringing the total number to 285, data from the China Securities Regulatory Commission showed on Thursday.

China's currency, the yuan, is convertible for trade purposes under the current account, while the capital account, which covers portfolio investment and borrowing, is still largely controlled by the state over concerns of abrupt capital flows in and out of the country.

To gradually open the capital account, the government introduced the QFII and RQFII (Renminbi Qualified Foreign Institutional Investor) programs in 2003 and 2011 respectively. They give overseas investors the right to move quotas of money into the account, to encourage controllable flows.

As of May 29, overseas institutions received QFII quotas amounting to $74.47 billion. The volume under the RQFII scheme totalled 382.7 billion yuan.