Nasdaq OMX Group Inc. (NDAQ) said Monday it has put a temporary moratorium on business travel to Mexico, while other exchanges activated contingency plans in case the swine flu outbreak escalates into a pandemic.

Exchanges have stepped up contingency planning, including for health emergencies that may force staff and traders to work from home or a remote location, since the Sept. 11, 2001, terrorist attacks closed U.S. financial markets for several days, .

New York-based Nasdaq OMX joins a list of corporations worldwide that are limiting travel to Mexico, the center of the swine flu outbreak. The number of confirmed cases in New York may climb toward 100, but the cases so far have been confined to a parochial school in Queens.

Silvia Davi, a spokeswoman for Nasdaq OMX, said the exchange is reviewing all business travel plans in light of the swine flu situation, ensuring employees steer clear of Mexico.

In a memo circulated Monday, Nasdaq OMX staff were also prepared for the possibility of telecommuting if the problem deteriorates, she said.

Contingency plans were also activated at other exchanges, though officials declined comment on specific details, citing security concerns.

Chicago-based CME Group Inc. (CME) on Monday circulated its own memo to employees and exchange members, passing along swine flu information from the Centers for Disease Control and flu prevention tips.

"We believe these proactive actions help to ensure the well-being of the CME Group community," CME said in a statement.

ChicagoFirst, a business continuity non-profit group that counts CME, NYSE Euronext (NYX), the Chicago Board Options Exchange and the Options Clearing Corp. as members, distributed information from city and state officials.

"Exchanges and other members do have within their plans work-from-home and telecommunications provisions," said ChicagoFirst Executive Director Brian Tishuk, in an interview with Dow Jones Newswires. "To the extent that's feasible, they do plan to do that."

Tishuk said member companies of ChicagoFirst, which has had a pandemic working group in place since 2006, have tested their crisis-response plans within the past year.

-By Jacob Bunge, Dow Jones Newswires; (312) 750-4117; jacob.bunge@dowjones.com