Russia's foreign minister on Tuesday rejected speculation that a hijacked Russian-crewed freighter was carrying S-300 missiles possibly destined for Iran.

The freighter Arctic Sea was allegedly seized by pirates in the Baltic Sea in late July after leaving a Finnish port. Russian naval vessels intercepted the ship weeks later off Cape Verde, thousands of kilometers from the Algerian port where it was purportedly supposed to deliver a load of timber.

But an array of questions continue to cloud the incident. Some observers have suggested that the seizure of a ship in the crowded Baltic, especially one carrying a comparatively low-value cargo, was unlikely as an act of straightforward piracy.

A Russian shipping expert and an EU anti-piracy official have speculated that the vessel was carrying a clandestine cargo, possibly S-300 surface-to-air missiles for Iran or Syria.

But Lavrov said Tuesday that "the presence of S-300s on board the Arctic Sea cargo ship is a complete lie," the state news agency RIA Novosti reported.

Separately, Russia's top investigative body, the general prosecutor's Investigative Committee, said its inspectors had examined the ship and found no unauthorized cargo, RIA Novosti said.

Suspicions that the Arctic Sea was carrying something other than timber also arose when Russia sent three heavy-lift air force jets to Cape Verde after the ship was found. The planes had far more capacity than would have been needed to bring the eight alleged hijackers and most crew members back to Russia.

Four of the crew members remained on board to help guide the ship to the Russian port of Novorossiisk, where authorities have said a thorough investigation of the ship will be held.

The crew members have been kept incommunicado. The eight suspects have been charged with piracy and are in custody, but Russian authorities have not given details of what they contend happened aboard the ship.

Lavrov said Russia would invite officials from Malta, under whose flag the Arctic Sea sailed, to take part in the inspection.

"All this will be transparent and I hope that all will be convinced that the rumors you refer to are groundless," Lavrov was quoted as saying at a news conference.

Russia has signed a contract to sell S-300s to Iran, but reportedly has not delivered any. Israel vehemently objects to Iran acquiring the missiles, which would significantly boost Iran's defense capacities.

The S-300, similar to the U.S. Patriot missile, is capable of shooting down aircraft, cruise missiles and ballistic missile warheads at ranges of over 90 miles and at altitudes of about 90,000 feet.

Israeli Foreign Minister Shimon Peres held talks in Moscow with President Dmitry Medvedev two days after the Arctic Sea was taken by the Russian navy. He said after the meeting that Medvedev had promised to reconsider selling S-300s to Iran.