(Adds commission spokesman comment, details on financing recommendations)
MEXICO CITY, Jan 23 (Reuters) - Mexico's antitrust watchdog on Friday warned some aspects of a new tender to build a high-speed train system would hinder fair competition, adding a new stumbling block for the government after a political scandal blew up around a previous contract.
Mexico's Federal Competition Commission issued a series of recommendations to change the terms of the new bid, arguing that some clauses would favor "some participants."
Late last year, China Railway Construction Corp (CRCC) and a group of Mexican partners won the tender to build the $3.75-billion rail line, but the contract was revoked and one of CRCC's Mexican partners sparked a conflict-of-interest scandal.
Last week, authorities revealed fresh preliminary bid terms for the train project linking Mexico City with the wealthy, industrial city of Queretaro.
The competition commission criticized specific technical and economic requirements in the new tender.
"The inclusion of a multitude of technical and economic elements could provide an advantage to some participants," the commission wrote.
Commissioners highlighted technical scoring requirements such as that the winning bidder must have already built at least 300 km (186 miles) of high-speed train tracks.
The commission did not specify any companies by name. A commission spokesman said the recommendations were not binding.
Sources with knowledge of the bidding have told Reuters that CRCC looks poised to clinch the new contract given its broad financing plan, which includes financing from the Chinese government, and political support in Mexico.
The commission also criticized a clause that required bidders to put together a financing package for the Mexican federal government that includes backing from export banks from countries that will send materials to Mexico.
Since taking office in 2012, Mexican President Enrique Pena Nieto has courted China's government and businesses to boost investment in Mexico. The high-speed train project was meant to be one his flagship infrastructure projects.
But controversy exploded when it surfaced that Grupo Teya, one of the Mexican firms in the CRCC-led consortium, was a subsidiary of a government contractor that owned a multimillion-dollar home Pena Nieto's wife was in the process of buying.
The government revoked the contract on Nov. 6, a few days before the Teya revelations were published.
Last week, companies were given six months to prepare their bids, but the commission said that countdown should only begin once all parties have had access to all the information needed to make a bid. (Reporting by Michael O'Boyle and Adriana Barrera; Editing by Clarence Fernandez)