A swine flu pandemic could lead contracts to be "meaningless", a legal expert has said.

According to David McIlwaine, partner at Pinsent Masons, commercial contracts carry clauses known as force majeure, which means in the occurrence of major unforeseeable events outside of either party's control  - such as mass staff absence - companies are relieved of their contractual obligations.

McIlwaine said: "If suddenly half your workforce is off sick and you are a major IT services company and obliged to deliver certain service levels then you might invoke the clause. It becomes even more difficult because probably your customer is operating with staff working from home."

According to Pinsent Masons, if an employer decides to employ the clause, it will be up to the courts to decide if the incident qualifies or not.

McIlwaine added: "If a government declares a state of emergency, for example, or if it says that people should not go to work, then that could have an impact, as could the definitions given. Whether the Government calls it a pandemic could be important."