BEIJING - China has seen 7 billion yuan ($1.03 billion) raised in the first bond issues by the country's non-financial firms under the mainland-Hong Kong bond connect program.

The bonds were issued by five companies, namely China Huaneng Group, China Three Gorges Corporation, China Unicom, Aluminum Corporation of China, and State Power Investment Corporation, on Monday and their book building processes were completed by Thursday noon, according to the National Association of Financial Market Institutional Investors (NAFMII).

Altogether 1.27 billion yuan of these bonds were purchased by more than 10 overseas investors, including Deutsche Bank, HSBC, and the Bank of East Asia, accounting for 18.2 percent of the total value.

The bonds were all oversubscribed by more than two times, the association said, noting strong intention of investment from overseas institutions.

Chinese authorities approved the bond link in mid-May, allowing investors from both sides to trade bonds on each other's interbank markets. "Northbound" trade, which allows foreign investors to buy bonds issued on the Chinese mainland, started Monday.

China has the world's third largest bond market, which is growing rapidly and opening more widely across the globe.

By the end of June, the country had seen the issuance of 71.4 billion yuan of panda bonds, yuan-denominated bonds sold by foreign issuers in China, according to NAFMII data.