The International Foundation of Employee Benefit Plans, which was planning to bring more than 10,000 visitors to Hawaii and rent about 5,700 hotel rooms next month for its annual conference, is threatening to cancel the event if there is the potential for a strike or other union action during their stay at the Hilton Hawaiian Village.

Hilton employees belonging to Unite Here Local 5 began a five-day strike early this morning over stalled contract negotiations.

The Brookfield, Wis.-based organization addressed its concerns in a letter Friday to Jerry Gibson, area vice president for Hilton Hawaii. In the letter, which was signed by foundation Chief Executive Officer Michael Wilson and President and Chair Simone Rockstroh, the foundation said “we will have no alternative but to cancel the conference for Hawaii” if labor issues are not resolved so that there are no activities such as strikes, pickets and boycotts.

Gibson said he was waiting to hear from the International Foundation today. The group has contacted other hotels in Waikiki to see if they could take the guests that were booked at the Hilton, Gibson said. The group had booked 9,230 hotel room nights (number of rooms times number of nights) at the Hilton, he said.

Gibson added that Unite Here Local 5 is calling convention groups asking them not to come to the Hilton Hawaiian Village.

The International Foundation said it may be able to find rooms at hotels without union issues. Cade Watanabe, spokesman for Unite Here Local 5, said he hopes the group can book rooms at other properties.

The foundation said it has more than 5,100 registrants for the Nov. 14-17 conference, with union members making up about 60 percent of that number. It said 80 percent to 90 percent of the registrants are “friends of labor” that will not cross a picket line.

Stacy Van Alstyne, director of public relations and advertising for the International Foundation, said this afternoon the foundation was aware that the strike had begun and “is continuing to monitor the situation.”

In the Friday letter, the foundation said it will need to make a decision either to proceed or cancel in the “very near future.”

The foundation said it has scheduled Hawaii as an annual conference site every five years since the 1970s, and if work actions cannot be avoided, that it is unlikely to bring a conference of this size back to Hawaii.