Ahmad Mahdavi added that until the end of the current fiscal year (March 20, 2019), petrochemical firms' foreign currency earnings would increase by 5-10%.
Mahdavi said the currencies have been offered through Nima, the local name for the Integrated Forex Deals System launched by the government after it unified the USD forex rate.
Petrochemical companies' export earnings account for the biggest portion of Iran's non-oil exports. These firms have in the past been accused of withholding their hard currency and not bringing it into the market, Financial Tribune reported.
According to Mahdavi, the hard currency presented by petrochemical firms last year totaled $8 billion, a portion of which was spent to repay foreign loans and purchase equipment.
The government decided to unify the US dollar's exchange rate at 42,000 rials on April 9 in response to volatility that saw the rial sink to all-time lows against the greenback.
It has since enforced a multi-tier rate scheme, based on which imports will receive their foreign currency at different rates as per the priority accorded to goods.
The least important class of imported goods, which the government has deemed "luxurious", faces an outright ban.
"Essential" goods such as staples like oil, rice and wheat will receive their currency needs from oil revenues at the 42,000-rial rate, which will be further subsidized to 38,000 rials.
The next priority includes "raw materials and intermediate goods", the forex requirements of which will be met from the export earnings of petrochemical, steel and mineral products at the 42,000-rial rate.