Mohamed El-Erian warned Tuesday that there's a major chance of a Greek "accident" happening, and he doesn't foresee a debt deal happening anytime soon.
The chief economic advisor at Allianz sees a 55 percent chance of a "potential for an accident happening" that would cause policymakers to lose control. El-Erian said that probability has risen as the Greek "economy has been imploding day in and day out."
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"The reason why is because of what's happening on the ground," he added.
El-Erian cited accelerating bank deposit outflows, capital controls and the issuance of IOUs among the problems that would hold back a deal that "buys time for Greece" to get its act together with its creditors.
In an interview with CNBC's "Halftime Report" on Tuesday, El-Erian called the potential upheaval a "graccident."
Still, he noted that he's a lot less worried about a possible contagion effect than he was back in 2012.
Greece, which may default on an International Monetary Fund repayment later this month unless it receives fresh funds, owes official lenders 242.8 billion euros ($272.9 billion), according to a Reuters calculation from official data.
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That figure combines two bailouts from European governments and the IMF since 2010 as well as holdings of Greek government bonds by the European Central Bank and national central banks in the euro zone.
Germany's exposure for the two bailouts totals 57.23 billion euros, France's is 42.98 billion euros, Italy's is 37.76 billion euros and Spain's 25.1 billion euros. That is in addition to their contributions to the IMF loans, commensurate with their respective quotas in the global lender.
But even with Greece's future in doubt, Europe is still a better place to invest than the U.S., according to David Herro, portfolio manager of the Oakmark International fund.
Oakmark, which is handily beating the S&P 500 this year, lists European banks among its top holdings.
Herro said Tuesday, also on "Haltime Report," that he is not scared off by the risks of a possible Greek default. Instead, he says his fund hunts for high-quality businesses no matter where they might be located.
"A lot of this has to do with the Greece instability and volatility causing people to shy away from European equities, thus providing opportunities for long-term investors," Herro said.
—Reuters contributed to this report.