BOSTON — Two top Federal Reserve officials argued for further aggressive action by the central bank, with one saying the economy needs “much more” help and the other pointing to Japan’s painful lessons.

With nearly one in 10 in the US labor force unable to find work and already very low inflation threatening to drop further, the Fed is expected to offer the economy more support at its next policy meeting, on Nov. 2 and 3.

Most analysts expect the Fed to embark on a fresh round of Treasury purchases, over and above the $1.7 trillion in longer-term assets it has already bought.

“In my opinion, much more policy accommodation is appropriate today,” Chicago Federal Reserve Bank President Charles Evans said yesterday at a conference hosted by the Boston Fed, repeating an argument he made earlier this month.

Boston Fed President Eric Rosengren, speaking at the same event, said Japan’s drawn-out battle with deflation shows prevention may be easier than the cure, and policymakers should respond aggressively before “pernicious” deflation takes hold.

“Insuring against the risk of deflation may be much cheaper than waiting until it has occurred and then trying to address it,” said Rosengren.