LONDON/ISTANBUL - Ukraine has requested that Turkey detain and arrest the Russian-flagged cargo ship Zhibek Zholy carrying a cargo of Ukrainian grain taken from the Russian-occupied port of Berdyansk, according to a Ukrainian official and document seen by Reuters.

The Ukrainian foreign ministry official, citing information received from the country's maritime administration, said the 7,146 dwt Zhibek Zholy had loaded the first cargo of some 4,500 tonnes of grain from Berdyansk, which the official said belonged to Ukraine.

In a letter dated June 30 to Turkey's justice ministry, Ukraine's prosecutor general's office separately that the Zhibek Zholy was involved in the "illegal export of Ukrainian grain" from Berdyansk and headed to Karasu, Turkey, with 7,000 tonnes of cargo, which is a larger cargo than cited by the official.

The Ukrainian prosecutor general's office asked Turkey to "conduct an inspection of this sea vessel, seize samples of grain for forensic examination, demand information on the location of such grain", the letter said, adding that Ukraine was ready to conduct a joint investigation with Turkish authorities.

A Russian-installed official in Russian-occupied areas of Ukraine's Zaporizhzhia region said on Thursday that after a stoppage of several months the first cargo ship had left Berdyansk port without naming the Zhibek Zholy.

Kremlin officials in Moscow did not immediately respond to a request for comment on Friday.

Ukraine has accused Russia of stealing grain from the territories that Russian forces have seized since its invasion began in late February. The Kremlin has previously denied that Russia has stolen any Ukrainian grain.

Turkey's foreign ministry did not immediately reply to a request for comment on the arrival of the Zhibek Zholy.

Kazakh based KTZ Express confirmed to Reuters the Zhibek Zholy was owned by the company but said it was taken under a bare boat charter - when no crew or supplies are involved in the lease - by Russian company Green-Line, which was not designated under any sanctions.

KTZ Express added that it was consulting the parties involved and would abide by all sanctions and restrictions. Green-Line could not be immediately found to request comment.

The Ukrainian foreign ministry official added that the vessel was heading for the Turkish port of Karasu.

The vessel reported its position at anchor close to Karasu port, Refinitiv ship tracking data showed on Friday. The data shows it crossing the Black Sea from near Crimea. It did not list Berdyansk as its destination in the past 48 hours - but tracking data relies on transponders updating their positions.

Earlier this month Russia's defence minister said the Ukrainian ports of Berdyansk and Mariupol, controlled by Russian forces, were ready to resume grain shipments.

Western countries have accused Russia of creating the risk of global famine by stopping Ukraine from exporting grain via its Black Sea ports. Moscow denies responsibility for the international food crisis, blaming Western sanctions.

(Reporting by Jonathan Saul in London and Jonathan Spicer in Istanbul, additional reporting by Tamara Vaal in Nur-Sultan and Omer Berberoglu in Istanbul; Editing by Frank Jack Daniel and Alison Williams)