Leaders of the G8 major economies have agreed new measures to clamp down on money launderers, illegal tax evaders and corporate tax avoiders.
Governments agreed to give each other automatic access to information on their residents' tax affairs.
They will also require shell companies - often used to exploit tax loopholes and invest money anonymously - to identify their effective owners.
The summit communique urged countries to "fight the scourge of tax evasion".
