An initial proxy vote on the takeover fell short of required shareholder support. As of the May 23 proxy voting deadline, 64.8 percent of shares voted were in favor of the deal, falling short of the required 66-2/3 percent support, Nordion said in a release.

About 71.4 percent of all outstanding shares had been voted by proxy on the deal.

Sterigenics, a sterilization services provider owned by private equity firm GTCR LLC, raised its buyout offer for Nordion to $758 million earlier in May from $727 million after Nordion received a rival bid from an unnamed buyer..

Sterigenics has refused to raise its offer further, Nordion said.

The shareholders meeting will now take place on June 3 in Ottawa. The deadline for proxy voting is Friday, May 30.

The delay will give shareholders more time to vote if they have not yet done so, or reconsider their current position, Tamra Benjamin, Nordion's vice-president of public and government relations, said in an email.

Nordion shares were slightly lower in New York and modestly higher in Toronto in early trading.

(Reporting by Rod Nickel in Winnipeg, Manitoba; Editing by Peter Galloway)