Passengers on low-cost carriers Scoot and Tigerair Singapore will soon be able to earn miles with Singapore Airlines (SIA) frequent flyer program, KrisFlyer.

SIA senior vice president of marketing and planning Lee Wen Fen says adding Scoot and Tigerair Singapore as KrisFlyer program partners is a "natural development" given both were part of SIAs portfolio of airlines.

While miles-earning opportunities are due to start at the end of 2015, KrisFlyer members will be able to use their existing miles to purchase travel vouchers for use on Scoot and Tigerair Singapore flights from April, SIA said in a statement on Tuesday.

SIA owns 100 per cent of Scoot, which began medium-haul services with widebody aircraft in 2012. SIA also holds a 55.8 per cent stake in Tigerair Singapore, a budget carrier flying short-haul routes using Airbus A320 aircraft.

Virgin Australia, which is 22.8 per cent owned by SIA, is also a KrisFlyer airline partner. Therefore, given KrisFlyer members can earn miles on and redeem miles on Virgin-operated services, it is conceivable that miles earned on travel on Scoot or Tigerair Singapore may be used to book travel on Virgins domestic and international network.

Also, members of both KrisFlyer and Virgins Velocity frequent flyer program have been able to convert KrisFlyer miles into Velocity points and vice versa since November 2014 under a scheme the two airlines say is a world-first.