Some leaders from the Group of 20 major economies have expressed fears about the potential negative impact of a U.S.-China trade war on the world economy at a session of their two-day summit that started Friday, a Japanese government official said.

But it remains to be seen whether the G20 can agree on a joint communique, as the United States and China, the world's two largest economies, have been engaged in tit-for-tat rounds of punitive tariffs on hundreds of billions of dollars of each other's imports.

At the Asia-Pacific Economic Cooperation summit last month, leaders of the 21 members failed to finalize a joint declaration for the first time since the forum began in 1993, against a backdrop of the deepening divide between Washington and Beijing.