Last checked at 
PRAGUE, July 30 (Reuters) - The Czech telecoms regulator hashad talks with potential bidders in an auction of mobilespectrum frequencies besides those that took part in an abortedsale in March, the office's head was quoted as saying onTuesday.
The Czech Telecommunications Office (CTU) expects to releasefinal conditions for the new auction of frequencies to buildfourth-generation mobile networks by the middle of August.
The country's three incumbent operators -- Telefonica CzechRepublic, T-Mobile and Vodafone --have already criticised the conditions, mainly one reservingspace for a new entrant.
Newcomer PPF Mobile Services, a unit of the PPF investmentgroup owned by Petr Kellner, the richest man in the CzechRepublic, took part in an aborted auction earlier this year andis also expected to enter the new auction.
But besides PPF, Hospodarske Noviny newspaper quoted CTU'shead Jaromir Novak as saying that the office has seen interestfrom other potential bidders.
"Last week we met with representatives of CitiGroup, whichare looking for investment opportunities for clients in easternEurope," Novak was quoted as saying.
A CitiGroup spokesman was unavailable to comment. A CTUspokesman declined to give further details.
CTU has set aside part of the 800 MHz band for the newentrant in a bid to boost competition.
However, Telefonica CR, a unit of Spain's Telefonica, has threatened to complain to the European Union,saying it would be disadvantaged by the auction conditions.
Novak said the office was ready for a legal dispute, thepaper said.
The new spectrum is strategically important because it willhost superfast mobile networks based on fourth-generationtechnology that will allow faster mobile broadband access.
