Singapore Prime Minister Lee Hsien Loong said he instructed Transport Minister S. Iswaran to go on leave as the city-state’s anti-graft agency started a probe, the first involving a cabinet minister in almost four decades. The Corrupt Practices Investigation Bureau uncovered a case and asked to open a formal investigation that would involve interviewing Iswaran and others, Lee said in a statement on Wednesday, without specifying the reasoning for the investigation or the target. “CPIB acknowledges the interest by members of the public in this case because a minister is being interviewed,” the anti-graft agency said in a statement.