New Delhi: India and Japan had mutually agreed to run indigenous bullet trains and deploy globally inter-operable signalling systems in the Mumbai-Ahmedabad high speed rail corridor, a senior official said. A joint call by the two nations was taken after Japanese suppliers did not place proposals aligned with timelines for operating the Surat-Vapi high speed rail section from 2027."This is a flagship project for India and Japan. Both countries are working on a common goal of commercial operations in 2027," a senior official told ET, adding Japanese experts are supervising work from the beginning of construction in 2021.India plans testing its home-made bullet trains in mid-2027 with civil work for the 97-kilometre Surat-Vapi high speed rail section completing this year. The railway ministry plans to kick off commercial operations for the country's first bullet train from August 2027.This project garnered attention last week after former Japanese law minister, Hideki Makihara, accused India of being a tough negotiator and alleged delays in the bullet train project. The ministry of external affairs later clarified that discussions with Japan on the high-speed train are progressing well.Indian officials working on the high-speed rail corridor said Makihara was not part of meetings on the bullet train project. Instead, representatives from Japan's ministry of land, infrastructure, transport and tourism have been coordinating on this project."All approvals of drawings, designs, construction schemes, and quality control are done by Japanese experts," the official said, noting decisions are taken jointly by the two nations for speedy operationalisation of the corridor.Makihara criticised Japanese Prime Minister Sanae Takaichi's visit to India and accused India of not relying on Japanese technology for the bullet train. He flagged the decision to opt for open-source signalling protocols instead of Japan's proprietary DS-ATC (Digital Automatic Train Control) in this project.Officials said trainsets, signalling and Operations Control Centre (OCC) are long lead items, requiring suppliers to start manufacturing well in advance.