Banks may be in sound condition post-Lehman Brothers, but the financial system could crack again if hit with a devastating cyber attack, J.P. Morgan Chief Executive Jamie Dimon warned on Thursday.

"I think the biggest vulnerability is cyber, just for about everybody" he told CNBC's Indian affiliate CNBC TV-18 on Thursday. "I think we have to focus on it, the United States government has to focus on it."

"We have to make sure because cyber — terrorist and cyber countries — they could cause real damage. We're already spending a lot of money and J.P. Morgan is secure but we should really worry about that," Dimon told CNBC-TV18's Shereen Bhan in New Delhi.

Dimon put inflation running too hot as his second biggest concern, warning the reactionary raising of interest rates from the U.S. Federal Reserve could be the cause of a "traditional" recession.

Industry experts have placed increasing importance on the threat of cyber warfare as attacks become more sophisticated.