Prime Minister Narendra Modi will flag off the Vande Bharat sleeper train between Guwahati and Kolkata later this month, railway minister Ashwini Vaishnaw said on Thursday.

"The services will become operational in the next 15-20 days, possibly around January 18 or 19. We have requested the prime minister and everything is clear. I will announce the exact date in the next two to three days," Vaishnaw said.

The 16-coach train, with a passenger capacity of 823, has a design speed of 180 kilometres per hour. It will operate at 120-130 kmph between the two cities, covering prominent districts of Assam and West Bengal.

Both states are scheduled to go to polls this year.

Calling the development a major milestone for the country, Vaishnaw said the ticket fares of the Vande Bharat sleeper train will be substantially lower compared to air travel.

"In Vande Bharat sleeper, the 3rd-AC fare will be around Rs 2,300, 2nd-AC around Rs 3,000, and 1st-AC around Rs 3,600, which will include food as well. The fares have been designed keeping the middle class in mind," the minister said.

Vaishnaw added that Guwahati-Kolkata air travel costs around Rs 6,000 to Rs 8,000. On per-kilometre fares, he said these would be Rs 3.8 per km for 1st AC, Rs 3.1 per km for 2nd AC and Rs 2.4 for 3rd AC.

The 16-coach train comprises 11 3-AC coaches, four 2-AC coaches and one 1-AC coach. Of the total 823 berths, 611 are in 3rd AC, 188 in 2nd AC and 24 in 1st AC.

Other features include ergonomically-designed berths with improved cushioning, automatic doors with vestibules for smooth movement, enhanced ride comfort through superior suspension and noise reduction, an automatic train protection system (Kavach), an emergency talk-back system and disinfectant technology to maintain high sanitation standards.

"The disinfectant technology will kill 99.9 per cent of germs. The same technology is being used on the Vande Bharat chair-car version," Vaishnaw said.

Production is being ramped up, and eight more trains will be ready in six months. "By this year, 12 trains will be ready. From next year onwards, production will ramp up rapidly as the entire supply chain will be in place by then," the minister added.

On catering, Vaishnaw said trains originating from Guwahati will serve Assamese cuisine, while those starting from Kolkata will offer Bengali food.