China will operate bullet trains to Tibet, close to the Indian border in Arunachal Pradesh before July this year, marking the opening of high-speed train services to all Chinese mainland provincial-level regions, a senior official has said.

A 435-km rail link to the regional capital of Lhasa will run Fuxing high-speed trains powered by both internal-combustion and electricity, Lu Dongfu, board chairman of China State Railway Group Company Limited, told state-run Xinhua news agency on Saturday.

Construction started in 2014 on the railway line connecting Lhasa with Nyingchi in eastern Tibet. It is the first electrified railroad in Tibet and is slated to begin operations in June 2021.

The track-laying work was completed by the end of 2020, the report said.

The railway has a designed speed of 160 km per hour, according to Tibet Railway Construction Company Limited, a subsidiary of China State Railway Group.

China aims to extend the total length in operation of its high-speed train network to around 50,000 km by 2025, up from 37,900 km by the end of 2020, Lu said.

The high-speed railway network will cover 98 per cent of cities with over 500,000 residents, he said.

China's self-developed Fuxing trains now operate at a speed range of 160 kmph to 350 kmph, Lu said.

China is ramping up the train network in the country's southeast Tibet Autonomous Region connecting its remote parts with the Chinese mainland.

Last December, the track-laying work was completed for a railway line linking the cities of Lhasa and Nyingchi in Tibet close to Arunachal Pradesh.

The Sichuan-Tibet Railway will be the second railway into Tibet after the Qinghai-Tibet Railway. It will go through the southeast of the Qinghai-Tibet Plateau, one of the world's most geologically active areas.

China has also included building of a "passageway" connecting Tibet with South Asia in the 14th Five Year plan which is due to commence from this year.

China will support Tibet in building the passageway to South Asia, the Xinhua report said, quoting the 14th plan document which was submitted to China's Parliament, the National People's Congress (NPC).

The annual session of the NPC began here on Friday.

"China's Tibet Autonomous Region will be supported to build an important passageway opening to South Asia" the report said.

Though the Xinhua report has not mentioned, China has been planning for long to build the Trans-Himalayan Multi-Dimensional Connectivity Network through Tibet and Nepal, as part of the Belt and Road Initiative (BRI).

Nepal under the present government of Prime Minister K P Sharma Oli has been firming up especially the trans-Himalayan connectivity network with China.