More than two years after the Scottish Government unveiled "hugely exciting" plans for a Scotland-wide travel smartcard, the Sunday Herald has learned that no ­implementation date is in prospect for the system that would "make it easier, more attractive and possibly cheaper" to travel around Scotland.

Plans for the Saltire Card - similar to Transport for London's successful Oyster card - which would allow ­passengers to travel the country with a single ­smartcard, were announced by then Cities Minister Nicola Sturgeon in October 2012.

Despite hopes from passenger transport groups and politicians that the system would be up and running in time for ­Glasgow's Commonwealth Games, ­Transport Scotland this week insisted that a deadline for the scheme to go live had never been set.

Green MSP Patrick Harvie said: "We need an explanation from ministers for the delay in progressing such a common-sense project."

All commercial bus operators in the country have already installed smartcard readers in their buses. By the time First ScotRail's franchise comes to an end in March, smartcard platform validators will have been installed in every station on the ScotRail network. Other operators such as the Glasgow Underground have also launched smartcard systems.

Before the system can work, ­agreement must be reached on the pricing and revenue-sharing of multi-operator, multi-modal tickets. In addition, a system that would allow the smartcard systems of different transport operators to interact will have to be co-ordinated by Transport Scotland, and some smartcard readers may need to be upgraded or replaced.

A spokeswoman for Transport ­Scotland said: "[We] continue the detailed and complicated work of developing a ­smartcard scheme compatible with all the public transport modes in Scotland … We are building on the success of last year's school transport smart pilots.

"We have also worked extensively with transport operators to roll out smart and integrated ticketing across their estates and we are currently working with operators to develop multi-modal, multi-operator commercial smart ticketing with several TS-led commercial products on course for launch in 2015."