Data Protection Commissioner Billy Hawkes has said his office has found Facebook to be "broadly-speaking compliant" with European privacy laws.
Mr Hawkes also said he had no problem with his office being challenged in court by campaigners who want Facebook to do more to protect the privacy of its users.
Spokesman for the "Europe v Facebook" group, Max Schrems said there are many issues with Facebook's use of data "below the surface", especially in the areas of transparency and control.
Speaking on RTÉ's Drivetime, he said: "Facebook is, for example, holding deleted information of people, or information that other people submitted to Facebook that shouldn't really be there," he said.
"The problem is mainly a transparency issue, that Facebook is not telling people what is going on on the platform.
“And a control issue, so that that if users, for example, click on a delete button, that data is actually not gone but still stored in the background."
Because its international headquarters are located in Dublin, the Data Protection Commissioner is responsible for monitoring Facebook's data use globally, with the exception of North America.
Mr Schrems is seeking final decisions on 22 complaints against Facebook filed with the Commissioner.
His group plans to appeal them in court to test whether they comply with European data protection laws.
In a statement to Drivetime, Facebook said two reports by the Commissioner showed that the company complies with European data protection principles, and Irish law.
"We have some vocal critics who will never be happy whatever we do and whatever the DPC concludes," added Facebook.
Speaking on the same programme, Mr Hawkes said his office has carried out a very detailed audit of Facebook, a company it prioritises for inspection because it is responsible to users around the world.
He said it made a series of recommendations, which have largely been implemented by the company and his office continues to liaise with Facebook on new developments.
"Broadly speaking, we found that they were complaint," he said.
Mr Hawkes rejected claims by "Europe v Facebook" that other watchdogs considered Ireland light on regulation, pointing out that his office took the main telecommunications companies to court yesterday on the issue of unsolicited texts.
He said he would not hesitate in taking the same action against Facebook if, in fact, they were not complying with the law.
He added that he had no issue with the "Europe v Facebook" decision to seek legal rulings.
"It's quite normal that our decisions would be appealed," he said.
"If Mr Shrems and his colleagues - once they ask us for formal decisions on their complaints, which they are entitled to - if they don't like those decisions they have every right to appeal them to the courts.
“We will of course defend whatever decisions we do take. And that's the way things should work."