Has Google Inc. (GOOG) been playing dirty with Android?  That's the allegation raised by some South Korean rivals.  The smartphone and tablet OS may be dominating in sales, but it's also drawing increasing antitrust scrutiny in both the U.S. and South Korea.

South Korea antitrust regulators' pending investigation of the Android accusations heated up this week with authorities raiding Google's Seoul offices, according to a Wall Street Journal report.   

In South Korea, search portal firms NHN Corp. (SEO:035420) and Daum Communications Corp. (KDQ:035720) have accused Google of using their control of Android to block rival search portals on smartphones.  The companies do not accuse Google of overtly blocking their portals, rather they say that Google's bundling of a search engine with Android and making it labor intensive to "swap in" a different search amounts to an anticompetitive tactic.

An NHN spokesperson commented, "It does not allow fair competition among search engines if Android-based smartphone users come across Google Search whenever they touch the search engine icon, whether they want it or not."

South Korea's Korean Fair Trade Commission (KFTC), the counterpart of the U.S. Federal Trade Commission, is tasked with investigating these antitrust investigations. 

Currently NHN controls 52 percent of South Korea's mobile search traffic, with Google controlling 16 percent and Daum controlling approximately 15 percent.  Android plays a key role in the South Korean market with top tech conglomerates Samsung Electronics Comp., Ltd. (SEO 005930) and LG Electronics Inc. (SEO:066570) using Android as their operating system platform of choice for tablets and smart phones.  

Google promises to work with the KFTC to resolve the dispute.  A spokesperson comments, "We will work with the KFTC to address any questions they may have about our business. Android is an open platform, and carrier and OEM [original equipment manufacturer] partners are free to decide which applications and services to include on their Android phones. We do not require carriers or manufacturers to include Google Search or Google applications on Android-powered devices."

This is the second time in just the last four months that South Korean police have raided Google's offices.  The prior raid came in May, for a separate issue that Google claims was an innocent mistake.  

Between 2006 and 2009 Google believes it "accidentally" collected a large amount of fragments of traffic on open wireless networks.  It says the collection occurred due to a piece of test code that was unwittingly incorporated into the Street View project -- Google's fleet of internet-equipped cars that offer a ground-level view of streets for mapping purposes.

In Europe Google has already been forced to hand data over to authorities.  And it faces further investigations in Canada and in four U.S. states.  In South Korea authorities are probing the incident thoroughly, combing through data they seized from Google's AdMob advertising service.

Google claims that it never used the collected data for advertising purposes, but South Korean authorities' thorough examination of AdMob would indicate that this might not have been the entire truth.  Nonetheless, Google has yet to face any official charges for the data collection in South Korea or elsewhere.

However, Google does face a broad antitrust probe in the U.S. and similar antitrust probes in the EU and Asia.  The company is also facing a pending class action lawsuit in the U.S. for the street view data collection and other U.S. lawsuits filed by mobile service providers who claim Google bullied partners into dropping their services.