FRANKFURT, June 21 (Reuters) - Germany’s Constitutional Court rejected on Tuesday a challenge of the European Central Bank’s emergency bond-buying scheme, clearing a never-used crisis fighting tool.

Conceived at the height of Europe’s debt crisis, the Outright Monetary Transactions (OMT) programme was launched as part of ECB President Mario Draghi’s pledge to do “whatever it takes” to preserve the euro, giving the bank broad powers to buy the debt of financially strained members.

The European Court of Justice has already cleared OMT but a 35,000-strong German group, including politicians and academics, asked the German court to dismantle it, arguing that it constituted illegal monetary financing, violating German law.

The German court earlier expressed reservations about OMT, arguing that it may exceed the ECB’s mandate, could violated the prohibition of monetary financing and did not place necessary limits on the bank. But it did not make a ruling at the time, referring the case instead to the European court in an unprecedented move. (Reporting by Frank Siebelt; Writing by Balazs Koranyi)