The suspected case of swine flu at Ernst & Young in New York City could mark the entry of the disease into the financial community.

A staff memo said the employee had become ill over the weekend after contact with a family member who had been exposed as a virus, and has now received treatment.

While E&Y said it believed the woman had contracted swine flu, it did not want to list it as a verified case. The firm stressed that it had taken appropriate steps to protect the health of other employees.

Elsewhere in New York City, the virus has been diagnosed in 28 students at a private school, which was closed temporarily. In all, swine flu has killed up to 149 people in Mexico, and a further 2,000 have fallen ill.