"Publishing these ridiculous smears that have been refuted by Czech officials shows just how worried the media bosses are by the prospect of a Labour government.
"They're right to be. Labour will stand up to the powerful and corrupt - and take the side of the many, not the few."
Mr Corbyn said the right-wing press had become less powerful in the era of social media and "their bad habits were becoming less and less relevant".
"A free press is essential for democracy and we don't want to close it down, we want to open it up. At the moment, much of our press isn't very free at all.
"In fact it's controlled by billionaire tax exiles, who are determined to dodge paying their fair share for our vital public services.
"Instead of learning these lessons they're continuing to resort to lies and smears. Their readers - you, all of us - deserve so much better. Well, we've got news for them: change is coming."
The BBC understands the phrase "change is coming" refers to Labour's plans to go ahead with a second stage of the Leveson inquiry into press ethics as well a review of media ownership and plurality.