Auckland rail fares are rising for the second time in under six months, by an average of about 6.5 per cent.

Although subsidised bus and ferry fares will remain unchanged for the next year, Auckland Transport announced last night that the price of train travel will rise on March 13.

That follows an annual review of all public transport fares, which the council-controlled organisation was keen to point out was separate from increases of 2 to 3 per cent in October reflecting the Government-imposed increase in GST to 15 per cent.

Chief executive David Warburton said the latest increases - ranging from 10c on a one-stage fare of $1.60 to 60c on the $8.30 for an eight-stage trip - were aimed at bringing them closer to bus tariffs.

They follow the $8 million additional cost of increasing train services by 21 per cent to 1950 trips a week, from a combination of greater frequencies and last year's reopening of the Onehunga branch line.

Auckland Council transport committee chairman Mike Lee, a critic of previous fare rises who is a member of the transport organisation's price-setting board, could not be reached for comment.

Campaign for Better Transport convener Cameron Pitches acknowledged passengers had to accept some of the cost of increased services, but said the fare rises would come at a particularly busy time when returning tertiary students would swell commuter ranks.

He also accepted Auckland Transport was trying to align the various fares preparing for a seamless electronic ticket for all travel, but said it should be more up-front about its strategy for achieving that.