Apart from participating in the summit Nov 26-27, Modi will travel from Vittamod to Janakpur by the 19-km land route and will perform a special puja in Janakpur, a revered Hindu shrine.
Modi had made public his desire to visit Janakpur and Lumbini during his first official visit to Nepal in August.
"We are informed that Prime Minister Modi will travel from Vittamod to Janakpur via land route and we are going to upgrade that particular road section," Ministry of Physical Infrastructure Secretary Tulsi Prasad Situala told the development committee of parliament Tuesday.
The house panel also instructed the ministry to upgrade the route as quickly as possible since it is in a dilapidated condition.
Modi might come first to Kathmandu and then travel to Janakpur or might go directly in Janakpur by road, Situala said, adding that keeping both these options open, work on renovating the road has started.
In Janakpur, he is likely to spend two hours in Ram-Janaki Mandir, and will also discuss with officials the Janakpur Border Development Programme.
A senior foreign ministry official also confirmed that Modi would visit Lumbini but details with the Indian side were yet to be discussed.
"We have already made a request to the seven (SAARC) member states to send their advance teams to asses the preparations related to the summit before the first week of November. After the visits of advanced teams from the member states, all itineraries will be finalised," said the official.
In Kathmandu Nov 25 Modi will engage in several bilateral meetings with Nepali leaders and visiting heads of state and government of the SAARC member states. He will also visit Pashupati Nath temple, sources added.
On Nov 26 and 27, Modi will participate in SAARC Summit, including the declaration ceremony. On November 28, before leaving for India, he will travel to Muktinath temple in Mustang for worship.
Sources told IANS that Modi will spend at least two hours in Muktinath and will leave for Lumbini. After completing his visit in Lumbini, Modi will leave for New Delhi, according to the preliminary itinerary.