(Bloomberg) -- Ukraine’s agricultural exporters have left around $3 billion of their revenues overseas since Russia invaded the country, adding to the pressure on the nation’s foreign exchange reserves, according to central bank estimates seen by Bloomberg News.  

That is 70% to 75% of what traders from various industries have kept outside Ukraine since the start of the war, a government official said, citing calculations from the National Bank of Ukraine. The person spoke on the condition of anonymity as the data isn’t public. 

It is also one of the reasons the government has tightened control over grains and oilseeds shipments. The Cabinet of Ministers will require exporters of such goods to either get licenses or provide value added tax records going back before the invasion, as Bloomberg reported last week. Shippers will also need to prove they are repatriating foreign currency.

The new rules come into effect in 10 days, and are valid through 2024, according to the decrees, which were published Wednesday.

Ukraine is a major exporter of agricultural commodities, a key source of its wartime revenues. Russia’s invasion has made some established, risk-averse traders stay away, but it’s also brought in many fly-by-night companies. The government aims to squeeze out such operators, repatriate more foreign currency revenue and raise tax collection as Ukraine’s international allies, providing billions of dollars of aid, scrutinize its anti-corruption efforts. 

Last month, central bank Governor Andriy Pyshnyi told Forbes Ukraine that exporters hadn’t repatriated $8 billion worth of foreign exchange earnings. He didn’t specify a time period but said that while some remittances were delayed, other “unscrupulous entrepreneurs” were not bringing back their earnings at all, making it a “matter of state importance, especially in wartime conditions.” That estimate covers the last 10 years, according to the official who spoke with Bloomberg.

However, the efforts are taking time and costs for crop traders are racking up as their cargoes suffer delays. Audits of exporters were among reasons that stalled agricultural shipments from ports in the Odesa region last week, triggering numerous complaints, while traders shipping grain through the Danube said issues related to export documents have caused big delays in recent weeks.

It is mandatory for Ukraine’s exporters to repatriate revenue within a 180-day period, a requirement that helps the National Bank of Ukraine to stockpile gold and foreign-currency reserves to prop up the hryvnia during the war. 

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