Luas operators are asking people not to visit its website after it was hacked overnight.
A team of engineers have taken the website offline completely as they look into the issue.
Anyone that visited the Luas website this morning was greeted with a message stating it had been hacked.
The apparent attacker said that it had written to the tram operators some time ago, claiming the website had “serious security holes”.
The hacker was threatening to publish all data if Transdev did not pay one Bitcoin, or around €3,400, within the next five days.
Operators have tweeted urging people not to visit the website as it has been taken offline, adding that they have a number of technicians working on the issue.