Former Deputy Prime Minister S. Jayakumar will join Drew & Napier in May as a consultant, the law firm announced in a statement on Thursday.

He will be a consultant to spearhead the firm's international law, international trade and constitutional law practices. He will work with clients as well as mentor the firm's lawyers, said the statement.

Drew & Napier chief executive Davinder Singh said the firm was honoured at the move of someone "universally acknowledged" as one of the best legal minds of his generation. "He will bring unrivalled experience and insight in the fields of international and constitutional law, as well as in other areas," said Mr Singh.

Prof Jayakumar will continue in his role at the National University of Singapore's Faculty of Law, even after his appointment at the law firm takes effect on May 1.