A special exemption to appointment rules has been granted to allow Sir Michael Rawlins to extend his tenure as chair of an expanded National Institute for Health and Clinical Excellence.

Usually a maximum tenure of 10 years is allowed - which Sir Michael will reach next April. But health minister Lord Darzi's next stage review published in the summer outlined a significant expansion of NICE.

Commissioner for public appointments Janet Gaymer has decided the expansion of NICE represents an "exceptional circumstance" and will therefore allow Sir Michael to compete with other candidates for the position of chair.

Interviews for the post are due to be held in February, the Appointments Commission announced today. If he is successful, Sir Michael will only be able to hold the post for another two years, whereas other candidates will be able to hold it for four.