In a statement, SCT said it has been instructed by Nieto to launch a new tender for the 210km line.

"In order to give more time and facilitate the possible involvement of a greater number of manufacturers, as well as to ensure absolute transparency, the federal government has decided to launch a new bidding process," SCT said.

Last month SCT announced it had received only one bid from a consortium of Chinese and Mexican companies, but also confirmed it had received letters of apology from 16 international companies including major suppliers such as Alstom, Bombardier and Siemens, which said they would not be able to participate.

The tender for the turnkey project was only launched on July 27 and critics in Mexico have argued that prospective bidders were given insufficient time to prepare technical and financial proposals.