A ship that was reportedly hijacked in the English Channel was carrying advanced Russian anti-aircraft missiles to Iran and had been tracked by Israel, the Sunday Times quoted sources in Russia and Israel as saying.

The paper also quoted the sources as saying that Mossad, Israel's intelligence agency, tracked the vessel and later tipped off Moscow that its cargo had been sold by former Russian military officers linked to the Russian underworld.

The Arctic Sea, which set sail from Finland on July 21 with 15 Russian crew members and a cargo of timber, failed to arrive in Algeria on August 4 as scheduled. The ship's signal had disappeared in the Atlantic in late July.

Russia sent naval vessels August 12 to search for the ship in the Atlantic Ocean. Days later, the government said it had found the Arctic Sea off West Africa and arrested eight hijackers.

But this version of events has been challenged by a number of sources.

Military officials believe a "cover story" was concocted, The Sunday Times reported, since any evidence that the Kremlin had let advanced weaponry fall into the hands of criminals or be sold to Iran would be highly embarrassing.

"The official version is ridiculous and was given to allow the Kremlin to save face," the British paper quoted a Russian military source as saying.

"I've spoken to people close to the investigation and they've pretty much confirmed Mossad's involvement. It's laughable to believe all this fuss was over a load of timber. I'm not alone in believing that it was carrying weapons to Iran."

The Sunday Times quoted the sources in Jerusalem and Moscow as claiming the ship actually had been loaded with S-300 missiles, Russia's most advanced anti-aircraft weapon, while undergoing repairs in the Russian port of Kaliningrad.

The air defense system could help Iran repel a possible Israeli strike against the Islamic Republic's nuclear sites. Iran has long been interested in buying the missiles from Russia, but Israel has sought to convince Moscow not to deliver the systems.

Israeli military sources said Israel received intelligence that weapons bound for Iran were being loaded in the port, according to the report. "A decision was then taken to inform the Kremlin," a source was quoted as saying.

The paper said sources in Moscow suggested Mossad may have played a part in the alleged hijacking by carrying it out via a criminal gang, who were unlikely to have known anything about a secret cargo. "The best way for the Israelis to block the cargo from reaching Iran would have been to create a lot of noise around the ship," said a former army officer, according to the report.

"Once the news of the hijack broke, the game was up for the arms dealers. The Russians had to act. That's why I don't rule out Mossad being behind the hijacking. It stopped the shipment and gave the Kremlin a way out so that it can now claim it mounted a brilliant rescue mission."

On Thursday, the Russian maritime expert who was among the first to raise the alarm about the mysterious disappearance of the Arctic Sea said he had fled the country after receiving a threatening phone call.

Mikhail Voitenko, the editor of the online Maritime Bulletin-Sovfracht, posted an article about the freighter's disappearance on August 8. He later speculated that the ship might have been carrying a secret cargo, possibly weapons.