KYIV (REUTERS) - Grain silos in Ukraine's second biggest port, Mykolaiv, were hit by Russian shelling of the city on Tuesday (Aug 30), causing a fire that was still burning on Wednesday, Ukraine's emergencies service said.

"As a result of the shelling of Mykolaiv, grain silos at an infrastructure facility in the Korabelny district caught fire," the emergencies service said on Facebook on Wednesday. "Firefighting continues."

It published photos showing holes in the metal roofs of at least two silos and fire brigades pouring water on damaged facilities. A 200 sq m area had been affected, it said, without giving any further details.

There are several major grain terminals in Mykolaiv, and some have already come under attack during the Russian invasion, which Moscow calls a "special military operation".

Ukraine is conducting a counter-offensive in the area, which has come under constant shelling in recent weeks, to try to push Russian troops out of the city of Kherson to the south-east and drive them back towards Crimea, which Russia annexed in 2014.

Viterra, partly owned by commodity group Glencore, is one of several international grain merchants with facilities in Mykolaiv, which lies on the Southern Bug river close to the Black Sea. Its port terminal caught fire in June but there was no information on whether it had been affected this time around.

Ukraine's grain exports slumped after Russia invaded the country on Feb 24 and blockaded its Black Sea ports, driving up global food prices and prompting fears of shortages in Africa and the Middle East.

Three Black Sea ports were reopened under a deal signed on July 22 by Moscow and Kyiv and the ministry said these ports are able to load and send abroad 100-150 cargo ships per month.

Ukrainian officials have said they also want to open Mykolaiv port for grain exports.