Japanese Prime Minister Shinzo Abe said on Monday he has instructed Finance Minister Taro Aso to watch currency markets "ever more closely" and take steps if necessary, in the wake of Britain's historic vote to leave the European Union.

Abe's comments at an emergency meeting between the government and the Bank of Japan come as some analysts raised the possibility of the BOJ holding an unscheduled policy review ahead of the regular meeting later in July to offer additional stimulus.

"Risks and uncertainty remain in financial markets," Abe said.

"We need to continue to work toward market stability," he said, signaling Tokyo's readiness to conduct yen-selling intervention in the market if it deems yen rises as excessive.

Abe summoned Aso and Bank of Japan Deputy Governor Hiroshi Nakaso to discuss how to deal with the market turbulence caused by Brexit.