Two Hong Kong-listed companies are raising around $630 million in total through bond offerings, as more companies seek to tap debt capital markets to fund their businesses.

Pharmaron Beijing is planning to issue dollar-settled zero-coupon convertible bonds worth 2.18 billion yuan, equivalent to $324.3 million, it said Thursday. The bonds will mature around end-August next year, it said.

The Chinese contract research and manufacturing company, which provides services to the pharmaceutical and biotechnology industries, aims to use net proceeds from the deal to support its expansion, refinance some existing debt and for general corporate purposes.

Separately, China Nonferrous Mining is proposing to issue $300 million of zero-coupon convertible bonds due 2031. The Chinese miner is seeking to use the net proceeds to fund the construction of a sulfide ore resource development project in Zambia, the Beijing-based company said Thursday.

More Chinese companies are tapping Hong Kong's market as they seek different pools of capital to fund operations via share offerings and bond issuances. Hong Kong is widely seen as a gateway for foreign investors to allocate capital to Chinese assets, given the hurdles foreign capital faces in accessing the country's onshore markets.