A French competition watchdog accused Google today of unfair practice by blocking a company from advertising on its online search services.

The Competition Authority said Google had without warning blocked the account of Navx, a provider of road travel data, for Google's online advertising service AdWords, and ordered the US Internet giant to reopen it.

"The content policy of Adwords was implemented by Google in conditions that lack objectivity and transparency and which lead to the discriminatory treatment of providers of databases on (roadside) speed cameras," it said in a statement.

Google's Adwords service allows advertisers to bid for priority in having their products flagged up next to users' Internet searches.

Navx provides access to databases that warns drivers, via their GPS navigation systems, where speed cameras are located as well as providing information on service stops and fuel prices.

Navx complained to the authority that Google had "unilaterally suspended" its Adwords account on the grounds that advertising for such systems was against its content policy.

Reacting to the statement, Google acknowledged that it had been asked to clarify the policies that determine what advertising content it allows to accompany its search results.

It did not immediately specify why the Navx ads had fallen foul of the content requirements.

"A final ruling remains to be issued, and we remain confident of a positive outcome," the company's Paris office said in a statement sent to AFP.

"The French authorities acknowledge Google's rights to set clear content policies to guarantee that ads are appropriate."

Google, the world's most popular search engine, has been probed by US, German and Italian authorities on accusations of abusing its dominant position and EU competition authorities say they have also received complaints.

The French authority said most of Navx's advertising budget was spent on online ads, obliging it to use Adwords since Google is used for nine out of 10 Internet searches in France.

Navx said its revenues from online orders by individuals fell by 70 per cent when its Adwords account was suspended, and it was demanding compensation.

The authority said a final decision was due in the coming months.