Singapore Airlines will reduce its A380 services to Sydney and Melbourne, leading to a further cut in capacity on the Australia-Singapore route following recent changes to Qantas' schedule.

From May 30, Singapore Airlines will offer one daily A380 return flight from Sydney to Singapore rather than two and from October 26 it will no longer offer a daily A380 service from Melbourne to Singapore.

A Singapore Airlines spokeswoman said the flights would be downgauged to 777-300ERs as a result of operational requirements across the airline's network.

Singapore Airlines is deploying A380s into the Indian market for the first time from late May after that nation's aviation regulator rescinded a long-standing ban on the aircraft.

The 777-300ERs to be deployed on the Sydney and Melbourne flights have 278 seats, versus the 471 available on Singapore Airlines' A380s.

The smaller aircraft also lack the spacious first class suites available on the A380. However, Singapore Airlines will maintain its frequencies of four flights a day from Singapore to Sydney and to Melbourne.

The spokeswoman could not comment on whether the A380 services would be reinstated in the future.

Singapore Airlines has been struggling to fill seats on flights to Australia after a steep increase in capacity, with its load factor on flights to the south-west Pacific region falling to 74.3 per cent in March from 77.4 per cent last year.

Qantas, facing similar issues, announced in February it would cancel flights from Perth to Singapore and reduce the size of aircraft on its Sydney-Singapore and Brisbane-Singapore routes to A330s from larger 747s.

The overcapacity on the Australia-Singapore route, also serviced by budget carriers Jetstar, Scoot and Tigerair, has led to a decline in yields, or returns on fares.

Singapore Airlines is offering economy-class return fares from Sydney to Singapore from $746, while Qantas has fares of $699 on offer on the route.

The New Zealand-Singapore direct market is far less competitive. The Singapore Competition Commission has approved a proposed alliance between Singapore Airlines and Air New Zealand on the route.

The regulator found the alliance, which is meant to help the carriers better compete against the Qantas/Emirates partnership, could raise competition concerns but those would be offset by net economic benefits to Singapore.

Jetstar, the only competition to Singapore Airlines on the Auckland-Singapore route, announced it would abandon the route from July after the Singapore Airlines/Air New Zealand alliance was proposed in January.