MOSCOW, Feb 24 (Reuters) - Ukraine's military has suspended commercial shipping at its ports after Russian forces invaded the country, an adviser to the Ukrainian president's chief of staff said, stoking fear of supply disruption from the leading grain and oilseeds exporters.
Russia earlier suspended the movement of commercial vessels in the Azov Sea until further notice, but kept Russian ports in the Black Sea open for navigation, its officials and five grain industry sources said on Thursday.
Ukraine is a major exporter of corn (maize), much of it destined for China and the European Union. It also competes with Russia to supply wheat to major buyers such as Egypt and Turkey.
Egypt's state grains buyer cancelled an international purchasing tender for wheat on Thursday as the crisis led to reports that no offers of either Russian or Ukrainian wheat had been received.
Russian forces invaded Ukraine on Thursday in a massed assault by land, sea and air, the biggest attack by one state against another in Europe since World War Two.
"The market is still struggling to get a clear picture of the actual military situation on the ground. The ports in the Azov and Black Sea so far seem not to have been damaged according to the initial shipping agency reports," one European grain trader said.
The trader said the market was looking out for any declarations of force majeure, meaning suppliers will not fulfil contractual obligations because of extreme circumstances.
Shipping group Maersk said on Thursday it has halted all port calls in Ukraine until the end of February and has shut its main office in Odessa on the Black Sea coast, because of the conflict.
Russia, the world's largest wheat exporter, mainly ships its grain from ports in the Black Sea.
The Azov Sea's ports are shallower and have less capacity.