The Group of Seven leading economies agreed to hold an emergency phone meeting of finance ministers and central bank governors on Monday, Kyodo news agency reported on Sunday.
At the meeting, Finance Minister Yoshihiko Noda is expected to pledge that Japan will continue to buy U.S. Treasuries, Kyodo said without citing any sources.
The ministers will likely discuss measures to prevent turmoil in financial markets amid U.S. and European debt problems, it said.
Japanese government sources have said the G7 finance leaders will likely hold an emergency phone meeting, probably before Asian markets open on Monday, to discuss the twin debt crises in Europe and the United States, and may issue a statement after the meeting.
(Reporting by Leika Kihara, Editing by Jonathan Thatcher)