Visiting Chinese President Xi Jinping agreed Saturday with his Iranian counterpart Hassan Rouhani to help construct Iran's high-speed train system as part of China's "One Belt and One Road" initiative to build a modern "Silk Road."

Xi said during a joint press conference with Rouhani after their meeting in Tehran that China will cooperate in building a rapid train system between Tehran and Mashhad, and provide necessary financing for the projects.

The two leaders also saw the signing of 17 bilateral agreement documents for cooperation in fields such as infrastructure improvement, investment and the environment during a ceremony broadcast live on state television.

Xi was the first foreign leader to visit Iran since international sanctions against the Middle East country were lifted about a week ago under a nuclear deal reached last summer.

Rouhani noted that Saturday marked a "new chapter in relations between Iran and China."

He said the two sides agreed to expand bilateral trade to $600 billion in the coming 10 years.

The amount of trade between Iran and China was about $52 billion in 2014 but dropped to $42 billion last year due to falls in oil prices and sanctions against Iran, the Iran State News Agency reported Friday.

The two countries also agreed to cooperate on the peaceful use of nuclear energy.

A joint statement issued after the talks between Xi and Rouhani said the friendly ties between China and Iran have been elevated to a strategic partnership.

Xi was in Iran on the final leg of his foreign trip that also took him to Saudi Arabia and Egypt.