The Cross-border RMB Index (CRI), an index tracking cross-border yuan trading activities, continued an upward trend in May, showing a steady outflow of the Chinese currency, according to the latest data released by Bank of China (BOC) over the weekend.

The CRI in May reached 246, up 4 points compared to a month earlier, and 18 points over December 2013, BOC said in a report on Saturday.

The index is released monthly since April, instead of quarterly.

"The index is significant in terms of tracking the vitality of the cross-border use of the yuan. It is a transparent indicator for the international market," Wang Sanshou, executive director of Beijing-based Heading Century Consulting, told the Global Times on Sunday.

BOC, the country's third largest lender by assets, publishes the index because it has the advantage of an extensive overseas network, Wang said.

The cross-border circulation of yuan-denominated funds continued to produce a net money outflow, but at slower growth, BOC said in the report.

In May, cross-border yuan settlements amounted to 594.2 billion yuan ($95.78 billion), an increase of 52.6 percent from a year earlier but a slight fall of 3 percent from April. The current account for trading in goods and services remains the main channel for the yuan's cross-border flow.

Yet the increasing use of the yuan under the capital account, especially for direct investment, pushed the May index higher.

In May, the yuan settlement under direct investment reached 78.8 billion yuan, including 16.5 billion yuan for outbound direct investment, a surge of 364.7 percent from a year earlier.

With more Chinese enterprises going global, the use of the yuan in direct investment are expected to grow faster, Liu Xiao, a senior analyst at Beijing-based Anbound Consulting, told the Global Times on Sunday.

The use of the yuan between Chinese multinational corporations' headquarters and their overseas branches for internal settlement would be a major growth driver for the yuan internationalization, Liu said.

Currently Asian countries and regions took the largest share of the yuan receipt and payment outside the Chinese mainland, the BOC report showed.

The combined cross-border yuan trading in Hong Kong, Macao, Taiwan as well as Singapore, Japan, South Korea and Vietnam accounted for 77.5 percent of total offshore yuan trading.

Offshore yuan trading in Europe was also on the rise, accounting for about 8 percent of the global share. Yuan-denominated transactions in Germany, the UK, Luxembourg and France doubled from January to May from a year earlier.

The share of European yuan trading could pick up further with more Chinese enterprises investing in the European continent, Liu said.

The cross-border yuan settlement with Australia and the US also jumped, with the value close to 80 billion yuan each for the first five months, the bank said.

The yuan ranked seventh in terms of global settlement with a share 1.47 percent in May, up 0.04 percentage points from April, according to the Society for Worldwide Interbank Financial Telecommunication in June.

China has recently quickened the pace of internationalizing its currency.

The People's Bank of China (PBC) designated on June 18 China Construction Bank as the clearing bank for London during Premier Li Keqiang's visit to the UK. One day later, it appointed Bank of China for providing the yuan clearing service for Frankfurt.

On June 29, the PBC said it signed yuan clearing service arrangements with Paris and Luxembourg, symbolizing a full coverage of the Chinese currency in the European continent.

On July 4, the PBC announced setting up yuan clearing service in South Korea and appointed Bank of Communications as the clearing bank for Seoul, during Chinese President Xi Jinping's visit to that country.

Xi's visit also led to an agreement on direct trading between the yuan and South Korean won, the sixth such foreign currency after the British pound, the Australian and New Zealand dollars, the Japanese yen and the US dollar.