Mexican President Andres Manuel Lopez Obrador on Tuesday defended his government's move to speed up approval of major infrastructure projects considered vital to national security.
A decree published in the Official Gazette on Monday said that provisional authorization for public works in areas such as energy, tourism and transport must be issued within five business days.
Such infrastructure projects are in the "public interest" and part of "national security," it said.
Lopez Obrador has championed several megaprojects such a new Mexico City airport and his "Maya Train" that will link Caribbean resorts with ancient archaeological sites.
Legal challenges have led to delays, which experts said the decree appeared aimed at preventing in the future.
In the case of the Maya Train, indigenous communities allege that the railway will destroy fragile jungle ecosystems, and argue that prior consultations were insufficient.
Lopez Obrador rejected suggestions that the decree would make it hard to audit his flagship projects.
"It has nothing to do with transparency," he told reporters, saying government ministries were obliged to produce accounts.
"We all have the conviction to act honestly, (with) zero corruption," he added.