TEHRAN, Iran — Iranian President Hassan Rouhani has inaugurated a newly built extension to the country’s main Arabian Sea outlet, the port of Chahbahar on the Gulf of Oman.

The $340 million project was constructed by a Revolutionary Guard-affiliated company, Khatam al-Anbia, the largest Iranian contractor of government construction projects.

The extension involved several subcontractors, including a state-run Indian company. It brings the capacity of Chahbahar, Iran’s closest sea link to the Indian Ocean, to 8.5 million tons of cargo annually, from the previous 2.5 million tons.

It also challenges the Gwadar port, some 80 kilometers away (50 miles) across the border in Pakistan, which Pakistan has been building with Chinese investment.

Iranian state TV says Sunday’s inauguration was attended by dignitaries from India, Qatar, Afghanistan, Pakistan and other countries.