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

The Ukrainian foreign ministry official, citing information received from the country’s maritime administration, said the 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 said 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 – a larger cargo than cited by the official.

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

Kazakh-based KTZ Express confirmed the Zhibek Zholy was owned by the company but said it was taken under a bareboat charter 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.

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 denied that Russia has stolen any Ukrainian grain.

Kyiv’s ambassador to Ankara Vasily Bodnar said in early June that Turkish buyers were among those receiving grain that Russia had stolen from Ukraine, adding he had sought Turkey’s help to identify and capture individuals responsible for the alleged shipments.

Turkish Foreign Minister Mevlut Cavusoglu said last month that Ankara was investigating the claims but that the probes had not found any stolen shipments so far.

Ukraine and the West have accused Moscow of weaponising food supplies. Russia says Ukrainian mines laid at sea and international sanctions on Moscow are to blame.

The conflict in Ukraine has fuelled a global food crisis, prompting the United Nations to pitch the plan to reopen shipping routes from Odesa and other Ukrainian ports.

Turkey has pledged cooperation in establishing a protected corridor in the Black Sea to allow Ukraine to export its products.

Critics fear Russia will take advantage of the corridor to launch an attack on the strategic Odesa port.