(Adds commissioner comment on final decision date change)
MEXICO CITY, June 12 (Reuters) - Mexico's telecom regulator said on Thursday it would postpone the first stage of a tender for two new national TV channels from June to September, citing a delay in laws that should set out details of a sector overhaul approved in 2013.
The Federal Telecommunications Institute (IFT) pushed back the start date for the bid process to Sept. 2 and 3. Bidders were originally asked to seek competition clearance from the new watchdog by June 16 and 17.
The reform aims to boost competition in the phone business dominated by tycoon Carlos Slim's America Movil, as well as broadcasting, where Televisa is by far the biggest player.
So-called secondary laws hashing out the fine print of the reform were due to be approved by December 2013, but political bickering and a heavy legislative agenda have delayed passage.
Given the lag, "there is no certainty about some issues that may affect stakeholders' business plans, which could create a disincentive for investment," the board said in a statement.
The delay means the Institute will not announce a final decision until June 10, 2015 though it had previously foreseen a March 25 announcement, IFT commissioner Maria Elena Estavillo told local radio following the statement.
The IFT set an 830 million peso ($63.92 million) minimum price in April for the two stations, whose tender was announced in March.
America Movil has about 80 percent of Mexico's fixed-line business via its Telmex unit and some 70 percent of the mobile sector through its Telcel subsidiary.
Televisa has more than 60 percent of the TV market and has long been accused of wielding too much political power.
($1 = 12.9850 Mexican Pesos) (Reporting by Alexandra Alper and Adriana Barrera; Editing by Lisa Shumaker and by Michael Perry)