The first inter-provincial loop railway line has been put into service in southwestern China on Friday, as the country's top railway operator unveiled a new national train operation plan to boost capacity of the country's trunk lines and cargo service.

The adjusted operation plan, effective on Friday, will witness the country's first high-speed loop line cycling three landlocked provincial regions – Sichuan province, Guizhou province and Chongqing municipality, China State Railway Group said.

The whole journey will only take about eight hours, which will greatly facilitate travel, especially for those in smaller cities, it added.

The new plan will also raise the number of passenger trains in service to 4,970.5 pairs, an increase of 130.5 pairs over the previous operation plan, the company said, adding it will strengthen the country's passenger transport service.

The high-speed railway line connecting Beijing and Zhangjiakou, co-host cities of the Beijing 2022 Winter Olympics, and its branch line Chongli railway, as well as rail routes linking Zhangjiakou and Hohhot of the Inner Mongolia autonomous region and Zhangjiakou and Datong of Shanxi province have seen strong market demand after opening by the end of last year.

A total of 44 pairs of passenger trains will be operated on these lines during weekdays, along with an additional seven pairs over the weekend, in a bid to enhance transport capacity and meet people's travel demands.

The country's railway freight capacity has also been optimized, with two additional trains added to the China-Europe freight train service, as well as one multimodal express train and one express cargo train. So far, the country has a total of 191 direct freight trains.