The government plans to compile punitive measures against Iran over its nuclear ambitions in early August, following the adoption of a resolution by the U.N. Security Council in June to impose new sanctions on Tehran, government sources said.

The move is aimed at signaling Tokyo's willingness to work in step with the United States, as Washington has enacted tough sanctions against Tehran over its uranium enrichment program that Western nations view as a cover for the production of nuclear weapons.

But one of the sources said the government should avoid worsening its ties with Iran because it is one of Japan's major suppliers of crude oil.