Euro zone finance ministers on Monday rejected an offer made by private creditors of Greece, sending negotiators back to the drawing board with the mission to further lower the coupon on the new bonds that would be issued in the restructuring.

The decision showed European policymakers are unable to agree to a middle ground and increase the risk of break up in the negotiations, said Hans Humes, chief investment officer at hedge fund Greylock Capital Management, who sits on Greece's steering debt committee.

"What's happened recently reminds me of Argentina," Humes said in an event organized by Bloomberg Link. "While I had a lot of optimism that we were not going the way of Argentina, we seem to be going that way."

The difficult negotiating process could be a "reflection of the advisers," Humes added, referring to Cleary Gottlieb, the same law firm that represented Argentina during its 2002 default and continues to defend the country against investors who still seek payment on their debt.

European policymakers have not made a clear counterproposal on a new coupon for the restructured bonds after rejecting the 4 percent rate offered by creditors, Humes said.

"They are not saying we propose to you 3.50 percent. We haven't gotten that. We just get a bunch of headlines," Humes told Reuters on the sidelines of the conference.

He said tweaking that coupon by 50 basis points would not make a huge difference for Greece's economic sustainability.

Humes, who will attend a meeting of Greek creditors in Paris this week, said the next few days will be crucial for the resolution of the Greek crisis. A disorderly default, he said, would have very negative ramifications in the euro zone.

"Everybody involved in this (need to) do a serious gut check - the Greeks, the Europeans, the banks, the funds. What are we working with here," he told Reuters.

(Reporting By Daniel Bases and Walter Brandimarte; Editing by Leslie Adler)