DHAKA, Bangladesh - Nobel laureate Muhammad Yunus challenged the legality on Thursday of a Bangladeshi government order dismissing him as the head of the microfinance bank he founded.

Nine members of Grameen Bank's board of directors backed Yunus, an outspoken government critic, by filing a separate petition to the High Court, his lawyer Sara Hossain said. The court heard arguments on Thursday and said it would rule on Sunday.

Bangladesh's central bank ordered Yunus out of the bank on Wednesday, arguing that the 70 year old had violated a law that makes retirement at age 60 mandatory. Grameen said it was exempt from the rule and Yunus would remain in his post.