NAIROBI - Somali pirates hijacked a Russian tanker carrying $52 million worth of crude oil and 23 crew on Wednesday, prompting Russia to send a warship to try to deal with the incident, officials said.

Pirates who hijacked the Russian-owned MV Moscow University tanker 350 miles (565 km) off the coast of Yemen warned against any rescue attempt, saying this would endanger the Russian crew.

"A Russian warship is moving towards the tanker," Russian defence ministry spokesman Alexei Kuznetsov said. The Chief of the Russian General Staff cut short a visit to NATO headquarters in Brussels to coordinate the military's response, he added.

Somali sea bandits continue to outwit an international fleet of warships in the busy shipping lane linking Europe with Asia, raking in tens of millions of dollars in ransoms.

One pirate who identified himself as Abdi said the tanker was heading to a pirate haven on the coast of central Somalia.

"Any attempt to rescue the ship will certainly endanger the crew. The ship will be docked at Garacad," Abdi told Reuters by telephone, adding it was too early to talk about a ransom.

Russia's permanent representative to NATO, Dmitry Rogozin, said the warship would not attack the tanker as the safety of the crew was the top priority, Interfax news agency reported.

The ship will reach the tanker at around 2100 GMT, he said.