The finance ministers of Europe's five largest economies called in a letter to Treasury Secretary Steven Mnuchin for the U.S. to rethink tax reform proposals that they said were discriminatory and could harm the financial sector and international trade.

In the letter, seen by Reuters, the finance ministers of Britain, France, Germany, Italy and Spain said a proposed excise tax would contravene World Trade Organisation rules and violate double taxation treaties and could hamper trade and investment flow between Europe and the U.S.

They also warned that a proposed "base erosion and anti-abuse tax" may target genuine commercial arrangements involving payments to foreign companies, harming international banking and insurance businesses and discouraging non-U.S. financial institutions from operating in the U.S.

"The inclusion of certain less conventional international tax provisions could contravene the U.S.'s double taxation treaties and may risk having a major distortive impact on international trade," the ministers wrote.