Nods and winks about the risk of a sudden rise in the yen that were the order of the day at the weekend’s Group of Seven meeting in Essen in Germany failed to achieve the desired effect, just as they had done at the previous meeting in Singapore last September.

G7 ministers and central bank governors stressed the risk of “one-way bets” for currency traders in remarks interpreted by Koji Omi, the Japanese finance minister, as referring to the carry trade, in which investors borrow in yen to invest in higher-yielding assets abroad.