A Japanese government official will offer a preview of the plan on Thursday at an anti-corruption summit hosted by British Prime Minister David Cameron, said the sources, who have direct knowledge of the matter.
Japan will provide a more detailed roadmap to countering tax evasion when it hosts G7 heads of state on May 26-27, said the sources, who declined to be identified because they are not authorized to speak to the media.
Governments across the world have begun investigating possible financial wrongdoing by rich and powerful politicians and business leaders after the leak of more than 11.5 million documents from Mossack Fonseca, a Panamanian law firm.
The so-called Panama Papers have revealed financial arrangements of prominent figures, including friends of Russian President Vladimir Putin, relatives of the prime ministers of Britain and Pakistan and of China's President Xi Jinping.