US legislation designed to press China to let its currency rise poses a "very severe risk" of a trade war and should not be taken up by Congress, House of Representatives Speaker John Boehner said yesterday.

"I understand that people are concerned about the value of China's currency. I'm concerned about it as well," said Boehner. "What I don't believe is appropriate is for the Congress of the United States to take this issue up and to do it within a legislative form."