The National Tax Service (NTS) has launched a tax probe into Google Korea. 

According to industry sources, the tax agency sent auditors to Google Korea's headquarters in Gangnam, southern Seoul on Wednesday, and secured accounting books and other financial records.

Observers believe authorities have launched an investigation into rumors of alleged tax evasion by high-income YouTube stars.

Google currently owns the global video streaming service, YouTube. 

During his parliamentary confirming hearing in October, NTS Commissioner Han Sung-hee said he supports a tax probe into high-earning YouTubers.

He said that such a tax probe has not been conducted but noted that 513 YouTubers have been notified to report their income and file taxes. 

Following a revised law approved by parliament last week, starting July next year, Google must pay value-added tax(VAT) for its domestic services in South Korea.

However, there are still no clear taxation standards for Google's app store Google Play which accounts for the largest portion of Google Korea's revenue.