Tax authorities raid Argentina's biggest newspaper

* Clarin would be hurt by proposed media reforms

* Tax agency says raid is routine

BUENOS AIRES, Sept 10 - Argentine tax authorities raided the offices of Argentina's biggest daily newspaper on Thursday, escalating tensions between the government and one of Latin America's largest media groups.

More than 150 tax officials carried out inspections at a Buenos Aires building housing the offices of Buenos Aires daily Clarin, which is owned by media and telecommunications company Grupo Clarin <CLA.BA>.

The raid comes as President Cristina Fernandez is pushing a new media reform bill that analysts say will weaken Grupo Clarin's role as the dominant media company in Argentina.

Fernandez's husband and predecessor, former president Nestor Kirchner, has publicly criticized Clarin's coverage of the government as biased and described the company as a "monopoly."

Clarin has responded with intensive negative coverage of the proposed media reform.

Grupo Clarin owns newspapers, television and radio interests, as well as cable and Internet access companies. Its share price closed down 1.6 percent at 6 pesos per share on Thursday at the Buenos Aires Stock Exchange as local television stations covered the tax raid.

A spokesman for the AFIP tax agency said the raid was aimed at examining the company's books and was similar to recent inspections carried out at other companies.

But Martin Etchevers, a Grupo Clarin spokesman, questioned the raid and said the company was being singled out.

"This kind of inspection has never occurred in the history of Clarin," he told a local TV channel.

Last week, the head of Argentina's broadcast regulator said he had vetoed the merger of the country's two cable TV operators owned by Grupo Clarin, a move that also drew criticism from company officials.

Argentine lawmakers are currently debating President Fernandez's media reform bill, which would overhaul the country's broadcast regulations, which date from the 1976-83 military dictatorship.