Using a low-profile fleet of ships under U.S. sanctions, Syria has this year sharply increased wheat imports from the Black Sea peninsula of Crimea that Russia annexed from Ukraine, a sign of tightening economic ties between two allies shunned by the West.

Wheat sent to Syria from the Black Sea port of Sevastopol in Crimea increased seventeenfold this year to just over 500,000 metric tons, previously unreported Refinitiv shipping data shows, to make up nearly a third of the country's total imports of the grain.

With sanctions making it more complicated for Syria and Russia to trade using mainstream sea transport and marine insurance, the two countries are increasingly relying on their own ships to move the grain, including three Syrian vessels that are subject to sanctions imposed by Washington, the data shows.