Former Federal Reserve Chairman Alan Greenspan, who was blamed by some economists for overheating equity and housing prices in the 1990s and 2000s, said that were he in the job today, he would take pre-emptive action to tackle asset bubbles if they were financed by leverage.

Greenspan, who argued in office that it was better to clean up after an asset bubble had burst rather than artificially prick it, told delegates at a conference hosted by Citigroup Inc. in London Thursday that he believed that argument is correct when a speculative boom isn’t financed by debt, mentioning the 1987 stock market crash as an example. If the overheating was caused by leverage, however, “then you’re going to have problems,” he said.

“Bubbles are aspects of human nature and you can try as hard as you like, you will not alter the path,” Greenspan told the audience at Citigroup’s European Credit Conference via a video link from Washington. “I still hold to the general view that unless you have debts supporting the bubble, I would just let it alone because certain things about human nature cannot be changed and I’ve come to the conclusion this is one of them.”

The former Fed chairman, who warned against “irrational exuberance” in stock markets as early as 1996, was faulted by some economists for not using higher borrowing costs to prevent equity prices from rising before the bursting of the so-called tech bubble in 2000. He cut interest rates afterwards to “mop up” the damage, which some analysts said led to an overheating in the housing market that partly caused the financial crisis.

Greenspan remained unapologetic about the tech bubble, saying in a December 2002 speech that central banks had “little experience” in dealing with market bubbles and that “dealing aggressively with the aftermath of a bubble” was “likely to avert long-term damage.”