The United States is negotiating with major importers of Iranian oil, including South Korea and Japan, about reducing their purchases as part of sanctions targeting Tehran’s central bank.

A delegation of senior South Korean officials is traveling to Washington Tuesday for talks that will include how much the country needs to cut its imports. South Korea gets about 10 percent of its oil imports from Iran.

The United States imposed sanctions on financial institutions that do business with Iran’s central bank, which is a clearinghouse for most of Tehran’s oil sales. The measure allows for exemptions to countries that reduce their imports.

Japan’s foreign ministry said Monday it has not reached any deal with the United States, but that talks about cutting its oil imports from Iran are ongoing.

The sanctions have led to fears of higher oil prices, which could in turn harm fragile economies. But other oil producers, led by Saudi Arabia, have said they can boost their production to maintain a steady supply.

The European Union has imposed its own ban on Iranian oil imports beginning July 1. The sanctions are part of a Western effort to put financial pressure on Tehran because of its disputed nuclear program, which the United States, Israel and other nations say is aimed at building atomic weapons. Iran says its program is for peaceful purposes.

Iran has responded by cutting its limited exports to France and Britain, and threatening to stop sending oil to other EU nations.

A team of senior U.N. nuclear inspectors is in Iran for two days of talks about the country’s atomic program. The visit began Monday and is the second by International Atomic Energy Agency inspectors in three weeks.