The European Union's General Court defended the European Central Bank for not disclosing a document that supported the regulator's decision to freeze the amount of emergency cash it was providing to Greek banks in 2015, Reuters reported.

The court ruled that the central bank was right to withhold the document to protect its "space to think," according to the March 12 report.

Former Greek Finance Minister Yanis Varoufakis and German Bundestag member Fabio De Masi will appeal the ruling, Reuters reported. Both previously said the ECB's decision was illegitimate and aimed at forcing Greece to yield in bailout talks with its lenders.

"Contrary to the applicants' claim, the ECB could legitimately take into account the hypothetical effects that the disclosure of the contested document could have on its space to think in 2015 and also after 2015," the judges said.

The ECB's decision forced the Greek government to temporarily close the banks and impose capital controls, which sunk the economy and weakened Greek Prime Minister Alexis Tsipras' negotiating position with lenders, Reuters said.