The question came after an Observer story described how Bloomberg's Family Foundation invested hundreds of millions of dollars in the Cayman Islands and other places.

The investments "are perfectly legally, fully disclosed, and they're appropriate to maximize the assets which I'm giving away to charities," Bloomberg said.

When asked specifically if he supports the investments being made overseas, Bloomberg said, "You cannot invest without investing around the world."

The comments came when Bloomberg spoke to reporters minutes after President Obama's speech about proposed Wall Street regulations. Bloomberg warned that overregulation and taxation could send businesses and jobs to less stringent countries.