The message from chairman Lim Boon Heng to major portfolio companies comes after the offshore rig-building unit of Keppel - in which Temasek has around a 20 percent stake - paid more that $422 million (306 million pounds) to resolve charges it bribed Brazilian officials.

While Lim did not name Keppel in his speech published on Monday, his remarks left little doubt about the firm in question and Temasek's aversion to corrupt practices.

"What happened recently was a shock, not just to the company concerned, but it really dents the reputation of Singapore and all the other Temasek companies," Lim said.

"In markets where practices are questionable and compromising integrity is required to win business or contracts, we have to be very clear – there is a bright red line our companies should not cross."

(Reporting by John Geddie; Editing by Shri Navaratnam)