BERLIN, Dec 14 (Reuters) - Germany"s opposition conservatives said on Tuesday they would file a complaint with the constitutional court about the new government"s plans to tap unused debt from this year"s budget for future spending on climate and economic transformation. The new government passed a supplementary budget on Monday to supercharge its climate and transformation fund with a debt-financed injection of 60 billion euros to allow more investments in the shift towards a green economy. The supplementary budget, passed unanimously by Chancellor Olaf Scholz"s cabinet, will channel 60 billion euros of unused debt in this year"s federal budget into the government"s climate and transformation fund for future spending. "This is highly questionable. We will have it constitutionally reviewed," Ralph Brinkhaus, leader of the CDU/CSU conservative bloc in the Bundestag lower house of parliament, said in Berlin. Berlin has taken up less debt than projected so far this year as tax revenues developed better than expected and fewer companies asked for pandemic emergency aid over the summer. Brinkhaus said funds already approved by parliament should not simply be used for other projects planned by the new coalition government of Social Democrats (SPD), Greens and liberal Free Democrats (FDP). "This is a paradigm shift in budgetary policy," he added. The budget manoeuvre would allow the ruling parties to make the most of a temporary, pandemic-related suspension of borrowing limits in the constitution. The budget compromise would enable new finance minister and FDP leader Christian Lindner to eye a return to the debt brake rule from 2023 and still allow more public investments needed to reduce carbon emissions in Europe"s largest economy. The coalition wants to deploy the funds to make critical public investments in climate protection measures - from charging points for electric vehicles to better insulating homes - and the digitalisation of the economy.