Mexico's transparency institute (INAI) has called on the environment ministry (Semarnat) to say whether explosives will be used in the construction of the Mexico City-Toluca railway.
The information was requested by a private party which wants to know the potential risks to the public and surrounding property, INAI said in a release.
Semarnat reportedly provided electronic links to the project's environmental impact statement and other documents. But, according to INAI, Semarnat failed to provide a categorical statement and only created uncertainty because it did not say whether the requisite information was in the documents the party was directed to.
This is the second time INAI, which can order any ministry to release information, has made a request in connection with the project.
Last month, INAI called on the transport and communication ministry (SCT) to disclose contractual and payment information corresponding to the third stretch of the line.
Construction of the 57km Mexico City-Toluca railway line has passed the 35% completion mark and early next year operational tests are due to start at Zinacantepec terminal, the SCT said in an H1 progress report.
Operational tests on the complete line will start in the fourth quarter of 2017, the ministry said, adding that by the end of this year work should be 70% complete.
The cost of the project has risen to 44bn pesos (US$2.39bn) from 42.7bn pesos last November because of cost adjustments, inflation and a weakening peso, the ministry has said.
The interurban railway will have six stations and be capable of transporting up to 230,000 people a day. Travel time is expected to be 39 minutes and trains will reach speeds of up to 160km/h.