EU's migration commissioner Dimitris Avramopoulos questioned the validity of the testimonies of the protected witnesses in the Novartis case in a memo he submitted to the Greek parliament on Wednesday presenting his arguments on the case.

The Commissioner is named as one of the 10 politicians who allegedly received bribes from the Swiss drugmaker. He had announced he would not be able to attend the debate in parliament in person, as he would be in New York for work.

"The case is not a simple investigation into criminal responsibility of politicians because, for the first time in the parliament's history, the House is faced with the extraordinary phenomenon of protected witnesses, which, after reading their testimonies, everyone has called, rightly I think, 'hooded witnesses'," he writes.

Avramopoulos questioned whether the testimonies of those witnesses serve public interest, calling them "false witnesses" and "enemies of democratic legality".

"We also have to discuss if any illegal activity by Novartis in Greece started abruptly in 2006 when I assumed duties as the minister of health and was also abruptly stopped on January 26, 2015 and has since disappeared forever, as the protected witnesses are trying to persuade us with their testimonies," he added.