Unidentified hackers have gained access to the computer system of the Professional Golf Association and are holding some of its files for ransom, according to a report from Golfweek.

The hackers were able to encrypt some of the PGA's files and directed the association to an email address and Bitcoin wallet, according to Golfweek.

A PGA spokesperson said in an email that the situation is ongoing so it was declining to comment further, but added that there was no impact on the files for the PGA Championship, which starts on Thursday.

Cyberattacks in which hackers gain access to sensitive files, encrypt them and then ask for payment are known as ransomware.

Such attacks have become more common in recent years, with the WannaCry ransomware attack of 2017 making international headlines after hitting more than 200,000 computers around the world.

Ransomware hackers typically request cryptocurrency, often Bitcoin, which is difficult for authorities to trace.

The hackers had not explicitly asked for money yet but had offered to decrypt two files, Golfweek reported.

Mark Nunnikhoven, vice president of cloud research at technology security firm Trend Micro, said that ransomware attacks are very common but noted that this particular effort appeared explicitly targeted at the PGA.

Many cybercriminals use programs that automatically look for vulnerable systems to attack with ransomware in the hopes of making small amounts of money from a large number of victims, Nunnikhoven said.

The PGA hack appeared to be specifically targeted and explicitly timed to a major event, indicating that the association could be dealing with a particularly difficult situation, Nunnikhoven said. And the report that the hackers have not yet asked for a specific ransom amount and offered to decrypt some files adds to the evidence that the association is in a difficult position, he added.

"It’s worrisome in that it shows they know who they have on the line," Nunnikhoven said.