By Ken Parks 
 

BUENOS AIRES--Shares of Telecom Argentina SA (TEO, TECO2.BA) fell as much as 6.6% on Thursday after a top Argentine minister said the phone company's ties with another major telecommunications provider are a threat to competition.

Telecom Argentina's shares traded in New York fell 5.6% to $10.19, after hitting an intraday low of $10.08. Its shares in Buenos Aires were down 5.8% at $13.10 minutes before the end of trading.

A company spokesman wasn't immediately available for comment.

"Without a doubt, the fact the government is still looking at a possible monopoly situation at Telecom and Telefonica" is weighing on the stock, said Leonardo Bazzi, head of research at brokerage Puente.

On Wednesday, Argentina's planning minister, Julio De Vido, hinted that the government will take another look at the complex shareholder structure that links Spain's Telefonica SA (TEF) to Telecom Argentina.

"In the case of Telecom and Telefonica, we are going to continue working to resolve the issue of an installed monopoly [situation]. We are going to be prudent but very firm in making decisions and setting a time frame to resolve these issues," Mr. De Vido said in televised comments.

Telefonica's Argentine subsidiary and Telecom Argentina--the country's largest telecommunications providers--were created from the privatization of state-run phone company Entel in the 1990s.

Telefonica holds an indirect stake in Telecom Argentina as a result of a convoluted transaction that saw the Spanish firm obtain an interest in Telecom Italia SpA (TI, TIT.MI) in 2007.

The Argentine government at one point opposed that transaction on the grounds that the Telefonica and Telecom Argentina tie-up had created a virtual monopoly. Argentina's antitrust agency approved the arrangement in 2010, when Telefonica agreed to give Argentine minority investors sweeping powers in Telecom Argentina.

Argentine President Cristina Kirchner has significantly expanded the reach of the state in the economy through heavy regulation and the nationalization of former state-run companies that were sold to private investors during the 1990s.

Argentina's largest oil company, YPF SA (YPF, YPFD.BA), airline Aerolineas Argentinas SA, a water utility, the post office and a handful of smaller companies have returned to the state fold during the governments of Mrs. Kirchner and her husband and predecessor, Nestor Kirchner.

Also weighing on the stock was Mr. De Vido's announcement that the federal government had decided to cancel the long-delayed auction of 3G wireless spectrum.

The government called off the auction due to antitrust concerns and because none of the companies that submitted bids met the minimum requirements, the minister said.

Instead, the spectrum will be given to state communications firm Arsat, which Mr. De Vido said will seek partners to offer wireless services.

That could mean more competition for Argentina's four incumbent mobile operators--Telecom Argentina and subsidiaries of Mexico's America Movil SAB de CV (AMX, AMOV, AMX.MX), Telefonica and U.S.-based NII Holdings Inc. (NIHD)--that submitted bids in the now-canceled auctions.

Telecom Argentina had long called on the government to make additional spectrum available so carriers can meet rising demand for bandwidth-hungry data services.

Argentina boasts one of the highest rates of mobile-phone ownership in the world, with about 55 million wireless subscribers in a country of almost 41 million people.

Mobile phone service is a key source of growth for Telefonica de Argentina and Telecom Argentina, who are saddled with the slow growth, or no growth, fixed-line businesses they inherited from Entel.

While fixed-line phone rates have been capped since early 2002, wireless rates aren't subject to government price controls.

Write to Ken Parks at ken.parks@dowjones.com