The pipeline is seen as a major step toward supplying natural gas to one of the country's deprived and least-developed regions. Zahedan has a population of more than 850,000, according to a 2011 census.
"We have delivered today on what was promised to the people of Zahedan two years ago … All cities in Sistan-Baluchestan will gradually start receiving natural gas," Rouhani said before departing for a regional summit in Islamabad scheduled to be held on Wednesday.
Almost two-thirds of Iran's gas output comes from South Pars field which is shared between Iran and Qatar.
Mohammad Hassan Tehrani, a local gas official, said on Tuesday that 1,300 kilometers of pipeline is required for supplying natural gas across Zahedan, which is expected to be completed by 2021. Plans call for gas supply to all cities in Sistan-Baluchestan, including Zabol, Khash, Konarak and Chabahar, as well as providing the province’s power plants with gas feedstock.
The project will prevent the emission of 1.8 million tons of carbon dioxide, 1,000 tons of carbon monoxide, 8,000 tons of nitrogen oxide and 24,000 tons of sulfur oxide.
Companies and utilities in Sistan-Baluchestan, including large cement manufacturing plants and a major water desalination unit, have reportedly been hurt as a result of repeated delays in developing gas supply projects and the increase in price of alternative fuels such as fuel oil.
