A super-cheap rail and bus ticket Germany rolled out this summer brought nearly two million tonnes of savings in carbon emissions, an industry association said as the country debates an extension.

The ticket, valid nationwide on buses, subways and regional trains for just €9 a month, was introduced in June as part of an inflation-busting package by the centre-left-led ruling coalition.

As the programme was set to run out tomorrow, the public transport association VDV touted its pollution savings of 1.8 million tonnes -- the equivalent of the annual C02 output from almost 388,000 vehicles.

One in ten users of the ticket said it prompted them to use public transport instead of cars for a least one journey a week, VDV said, citing a survey of 6,000 people per week.

In all, 52 million tickets were sold.

Ten million people who already have regular monthly public transport tickets also benefited from the cheap fares.

Chancellor Olaf Scholz himself has said the measure was "one of the best ideas" his government had introduced, and has promised to hold talks on whether there could be a longer-term measure.

With inflation far from curbed, calls have been growing for the ultra-cheap fare to be carried into the autumn and beyond.

Finance Minister Christian Lindner has however voiced opposition, warning that an extension would cost the treasury "over €14 billion".

Mr Scholz's Social Democrats have reportedly proposed a €49 monthly ticket.

With the haggling set to drag on, some districts have implemented their own follow-ups.

Berlin, for instance, has signalled plans to offer a €9 monthly ticket for inner-city travel for the last three months of the year.