Japan and Iran have reached agreement on an investment accord, which may give a boost to Japanese investments into the Islamic Republic once sanctions are lifted as early as next year, the countries' foreign ministers said in a statement.

Japan is keen to boost ties with Iran and invest in resource projects there, as well as increase crude imports from the Middle Eastern country.

Japan's crude imports from Iran plunged more than 40 percent from 2011 levels before tough Western sanctions were introduced in 2012 over Tehran's disputed nuclear program.

Foreign business delegations from Italy, France and others have flocked to Tehran ahead of the expected opening of markets in the oil-rich nation of 80 million people.

Japanese foreign minister Fumio Kishida reached an agreement on the investment pact during a meeting with the Iranian counterpart Mohammad Javad Zarif in Tehran on Monday.

"Both sides affirmed that further efforts will be made for the earliest possible conclusion and entry into force," the statement from the ministers said.

The Japanese government wants the agreement to come into force around the middle of next year, Japanese media reported.

Japan's top oil and gas explorer Inpex Corp, which in 2010 was forced to give up a stake inIran's Azadegan oil field because of the sanctions, was among dozens of companies that visited Iran in August.

Iran's chief negotiator for new oil contacts said last week the country would introduce more than 50 exploration and production projects to investors in the near future.

Iran's conservative-dominated parliament passed a bill on Tuesday approving its nuclear deal with world powers, signaling victory for the government over hardline opponents who worry the accord opens a door to wider rapprochement with the West.

This article was written by Aaron Sheldrick and Shri Navaratnam for Reuters on Aug. 24, 2015.