The Marshal Shaposhnikov, a Russian anti-submarine warship, is rushing to assist a China-bound oil tanker hijacked by Somali pirates nearly 350 nautical miles off the coast of Yemen.

All the 23 Russian crew on board The Moscow University are reported to have locked themselves in the Liberian-flagged ship’s radar room after the pirates boarded the vessel, according to the BBC.

Tanker operator Novoship said the 106,000t vessel was carrying 86,000t of crude oil worth $52m which belongs to Unipec, an oil trader affiliate of China’s Sinopec.

Numerous groups of pirates are currently holding more than 350 hostages as well as about 20 ships at various bases around Somalia.

The pirates attacked the vessel using automatic weapons, Novoship said.