German insurer Allianz SE (ALV.XE) chief executive Michael Diekman Wednesday said the timing of the call by Greek Prime Minister George Papandreou for a referendum on the latest bailout package from Europe is "very unfortunate" and may have a disastrous impact on the country.

Speaking at the B20 business summit ahead of the summit of the Group of 20 industrial and developing nations here in Cannes, Diekman said the need to implement changes to the European Financial Stability Facility agreed last week has become even more urgent as investors question the details of the agreement.

He also warned against a prolonged period of low interest rates and said a discussion with central banks needs to take place on the matter.

-By William Horobin, Dow Jones Newswires, +33 1 4017 1740;

william.horobin@dowjones.com