By Jonathan Saul
LONDON (Reuters) - Merchant ships remained backed up in lanes around the Black Sea on Monday as ports struggled to clear backlogs amid growing unease among insurers and shipping companies a day after a Russian warship fired warning shots at a cargo vessel.
Russia said its Vasily Bykov patrol ship on Sunday fired on the Palau-flagged Sukru Okan vessel after the ship's captain failed to respond to a request to halt for an inspection. After an inspection, the vessel continued its journey towards the Ukrainian port of Izmail along the Danube river, Russia said.
Kviv on Monday condemned what it called "provocative" Russian actions and called for decisive countermeasures by the international community.
Insurance industry sources said rates for additional war risk premiums remained stable on Monday, although there was a possibility of a rise if a ship was damaged or sunk.
The cost of a Black Sea war risk premium, which is typically renewed every seven days and is in addition to annual insurance expenses, was estimated at tens of thousands of dollars per ship for the voyage.
At least 30 ships had dropped anchor around Musura Bay in the Black Sea, which leads into a channel that links up with Izmail further along the waterway, tracking data from analytics company MarineTraffic showed on Monday.
There were at least 20 ships anchored leading up to Izmail. In addition, there were at least 35 commercial ships waiting close to the Romanian port of Constanta, 15 more than last week, the MarineTraffic data showed.
Many of the vessels had reported their destination as Romanian ports. Romania on Monday said that it aimed to double the monthly transit capacity of Ukrainian grain to Constanta to 4 million tonnes in the coming months.
Sunday's incident cast a pall over plans announced by Ukraine last week for a "humanitarian corridor" in the Black Sea to release cargo ships trapped in Ukraine's ports since the outbreak of war.
There are an estimated 60 vessels still stuck inside Ukrainian ports including Odesa, one of three terminals that were part of UN backed grain initiative (BSGI) that Moscow exited.
"The security guarantees given to shipping by both sides under the BSGI are no longer in effect which means that the Ukrainian Black Sea ports are effectively blockaded and out of use for commercial vessels," Norwegian ship insurer Gard said in an advisory note last week, adding that Ukrainian sea ports in the northwestern area were no longer "safe" ports contractually.
Moscow says it will return to the grain deal only if it receives better terms for its own exports of food and fertiliser. Turkish President Tayyip Erdogan, co-sponsor of the grain deal alongside the U.N., says he hopes to persuade Russian President Vladimir Putin to rejoin it at talks this month.
The Joseph Schulte was among vessels that remained stuck in Odesa.
"We continue to do everything in our power to enable the vessel to move, despite permits and the many variables involved," a spokesperson with Schulte Group, the parent of the vessel's German based manager BSM, told Reuters on Monday. "The situation remains complex."