Singapore Airlines has also frozen its intake of cadet pilots.
Singapore Airlines has asked its captains to volunteer for unpaid leave amid a global economic slowdown that has dented long-haul travel demand, the airline says.
The move came nearly a year after the company - considered a bellwether for the full-service airline industry - made a similar offer to its first officers.
The airline has also frozen its intake of cadet pilots as part of a slew of cost-cutting measures.
"Singapore Airlines (SIA) began offering voluntary no-pay leave to first officers in March last year and subsequently to captains who expressed interest," company spokesman Nicholas Ionides said.