St. Louis Federal Reserve President James Bullard speaks at a public lecture on "Slow Normalization or No Normalization" in Singapore May 26, 2016. REUTERS/Edgar Su/File Photo

LONDON (Reuters) - U.S. policymakers must remain vigilant to the threat of another financial crisis and cannot rely on current rules to protect against future shocks, St. Louis Federal Reserve President James Bullard said on Thursday.

Bullard’s comments come after U.S. Fed chair Janet Yellen said earlier this week that she does not believe that there will be another financial crisis for at least as long as she lives, thanks largely to banking reforms since the 2007-09 crash.

“Even when you put a good regulatory regime in place, the next crisis tends to develop through other channels that were not part of the previous crisis,” Bullard told reporters at an event in London.

“It’s appropriate for us as policymakers to be aware that new types of threats can arise and may lead to financial crises at some point and there’s no set of stagnant rules that fits everything.”