Asia’s big oil importers are planning to implement significant cuts in their imports of Iranian crude oil, hoping to fend off the impact of tightening US sanctions that make it far harder for companies across the world to do business with Tehran.

Japan, the world’s third-largest oil importer, is close to securing a deal with Washington under which it would avoid being penalised by US sanctions. The US measures, introduced at the start of this year, make it difficult for companies to do business with the Central Bank of Iran, which acts as the clearing house for all financial transactions relating to the country’s oil trade.

Tokyo has offered Washington a reduction in Iranian oil imports of between 10 and 15 per cent this year in exchange for a sanctions waiver by the US, according to a person involved in discussions. Without this sanctions waiver, Japanese companies would find themselves being shut out of US markets.