Japan's top city gas supplier Tokyo Gas is looking to add more U.S. natural gas assets, its president said on June 3, as it aims to expand its gas-related businesses in North America after its recent acquisition of a U.S. shale gas producer.

The Japanese company paid $2.7 billion to acquire Texas-based natural gas producer Rockcliff Energy in December and agreed to purchase a 49% stake in North American energy marketing and trading firm ARM Energy Trading in February.

"We would still consider investing in shale gas assets if we can acquire them at the appropriate price and in a competitive way," Tokyo Gas President Shinichi Sasayama told reporters on the sidelines of the Japan Energy Summit conference in Tokyo.

"But we are not only looking to upstream assets, but also to surrounding assets such as marketing, trading and storage batteries, so that we could link them together to build the total value chains," he said.

In Asia, Tokyo Gas is studying two liquefied natural gas-to-power projects at Quang Ninh and Thai Binh in Vietnam and hopes to start commercial operations in late 2027 and in 2029, respectively.

Asked about the timing of a final investment decision, Sasayama said that was unlikely before the end of the current fiscal year, which runs through next March.

Tokyo Gas, a major LNG buyer in Asia, has been diversifying its procurement sources, buying about 13 million metric tons of LNG annually from 13 projects in four countries.

Though the company still holds a high proportion of long-term LNG contracts, it is adjusting its portfolio to be more flexible by including term contracts of various durations and spot procurement, said Satoshi Tanazawa, the chief executive of Tokyo Gas' energy trading company.

"We are incorporating not only long-term contracts but also term contracts of 5- or 10-years, as well as spot purchases," Tanazawa told Reuters on the sidelines of the conference.

"We aim for a flexible structure to respond to any major changes in the business environment," he added.