Transport bosses in Greater Manchester are being urged to reconsider plans to increase tram fares by twice the rate of inflation.
Metrolink tickets are set to rise by an average of 6% next year, with some fares rising by 7.3%.
The Greater Manchester Integrated Transport Authority said fares had been frozen for the past two years, and trams and track had been improved.
But local MPs Graham Stringer and Tony Lloyd said the rise was "unjustified".
Mr Stringer, Labour MP for Blackley and Broughton, and Tony Lloyd, Labour MP for Manchester Central, tabled a House of Commons motion saying the decision was taken "without any consultation and at a time when services have been disrupted because of the extension of the Metrolink system".
'Lower than RPI'
They are calling for immediate consultation on the issue.
The rise means an adult peak-return fare will increase by 20p and a peak-return for a child by 10p, in the majority of cases.
An annual season ticket for an adult, from Altrincham to Manchester, will go up from £875 to £930.
A spokesman for the transport authority said the rise is lower than the change in the Retail Prince Index (RPI) in the past two years.
Councillor Ian Macdonald, authority chairman, said: "We have considered the latest fare changes, which come into effect in January, in detail and believe that they represent value for money, while also ensuring that the network can continue to compete with other types of transport in offering popular, good quality services."
He said the authority had considered a request by Mr Stringer for public consultation but said they thought it was not appropriate.
"It is our role to ensure that we balance Metrolink revenues against the growing costs of running, improving and expanding the network, he added.
"For passengers, there is no ideal time to increase fares but we can assure them - and Mr Stringer - that any change will always be the least it can be."