US Treasury Secretary Jacob Lew said Thursday that he was not worried about a potential financial bubble forming as Wall Street stocks racked up record highs.

"The analysis that I've seen doesn't give me reason to be worried right now," Lew said in an interview on US business news channel CNBC.

Lew nevertheless called for monitoring of the situation in order to avoid another crisis like the 2008 Wall Street crash that led to the Great Recession.

"I think one of the lessons we learned from 2008, 2009, is -- even when things are not a problem -- we always have to ask those questions," said the new Treasury chief, who took office on February 28.

The blue-chip Dow Jones Industrial Average on Thursday closed at a record high for the eighth day in a row, though the US economy remains sluggish and massive government spending cuts kicked in on March 1.

"We need to make sure that we have the transparency to see what's going on in firms and in markets," Lew said.

"We need to have the regulatory tools to deal with problems as they develop. That doesn't mean we should jump in when we don't see a problem."