Google is allegedly exposing children to obscene online content in South Korea, according to government officials quoted in local media reports. 

However, state ethics watchdogs claim that they have been unable to talk to the search firm because it does not have a local representative office, the Korea Times reported. 

Leading Korean search portals confirm that users are at least 20 years old before showing search results that contain sex-related keywords. Google's Korean search engine does not, the newspaper reported.

Because the search results page includes summary text taken directly from other websites, it may contain language deemed to be obscene.

Although the age of consent in South Korea is 13, the age at which people legally become adults and are able, for example, to marry without parental approval is 20.

Google has had trouble breaking into the Korean market, which is dominated by local companies.

The search giant's share of click-throughs has been estimated at between 10 and 17 per cent by various sources this year, with rival Yahoo holding about 30 per cent. 

"Google is not legally required to check whether internet users are over 19 years old before showing the search results for adult content," Han Meyong-ho, an official at the state-run Information Communication Ethics Committee told the Korea Times.

However, Han said that it would be "proper" for Google to check that users are adults in a similar manner to other popular Korean-language search sites, including Yahoo's Korean portal.

Despite Han's claim that his office had been unable to communicate with Google, the Korea Times said that it had spoken with an "unnamed Google official " in Korea.

According to the newspaper, the official claimed that Google was already filtering out adult-only sites from search results. This appears to be a reference to the company's SafeSearch technology.