Prime Minister Benjamin Netanyahu's trip to Moscow on Monday was part of quiet diplomacy between Russia and Israel over Russia's plan to supply S-300 anti-aircraft missiles to Iran, Haaretz has learned.

A senior government source in Jerusalem confirmed yesterday that Netanyahu was in Russia for talks on security issues, particularly the sale of Russian weapons to Iran.

The missiles could help Iran protect its nuclear facilities from attack.

The purpose of the prime minister's trip, disclosed to only a few government officials, was to persuade senior officials in Russia's government and security establishment not to move ahead on a deal to give Iran the missiles.

The discussion also dealt with Russia's refusal to back more sanctions against Iran over its nuclear program.

On Tuesday afternoon, Netanyahu called a meeting of his six senior cabinet ministers to report on his discussions in Moscow. Later in the evening, the prime minister visited the President's Residence in Jerusalem for a one-on-one meeting with President Shimon Peres.

Peres had met with Russian President Dmitry Medvedev a few weeks ago to discuss the Iranian missile transactions as well.

According to information Haaretz has obtained, Netanyahu met with officials in the Kremlin. However, spokesmen for Medvedev and Russian Prime Minister Vladimir Putin said they did not meet with Netanyahu on Monday, even though they did not deny Netanyahu was in Russia. The prime minister may have met with senior Russian security and intelligence officials involved in weapons sales to Iran.

Defense Minister Ehud Barak was apprised of the trip, as was Foreign Minister Avigdor Lieberman, who is currently in Africa. Netanyahu's military secretary Meir Kalifi and National Security Adviser Uzi Arad accompanied him to Moscow.

A government source said Netanyahu's visit was more about security matters than diplomatic issues.

"These are matters of war and not matters of peace," the source said. The source said the talks were mainly about Russia supplying weapons to Iran, particularly S-300 anti-aircraft missiles. These missiles, if deployed near Iranian nuclear sites, would make an attack on them very difficult.

The frequent talks between Israel and Russia on the matter of the missile sales began after Lieberman visited Moscow in early June. At the time, Medvedev told Lieberman that due to the economic crisis, Russia was seriously considering selling the missiles to Iran, contrary to long-standing policy.

Israel then launched an international campaign against the potential sale. Netanyahu asked his counterparts in the United States, Britain, Italy, Germany, France and other countries to pressure Russia not to go ahead with the deal. Netanyahu also called Putin at the end of June to ask him to stop the deal.

The Russians, however, did not do so, and about a month ago, Peres went to meet Medvedev in Sochi on the Black Sea coast. During their three-hour meeting, Peres urged him to stop the missile sale. At the end of the conversation, during which tones became strident, Medvedev told Peres: "In light of your remarks, I will do homework on the subject."

A few days later, Medvedev told Israel he wanted to hold secret talks on the matter of the missiles, which began recently between the defense ministries of the two countries. However, Netanyahu's visit was apparently intended to exert heavier pressure on the Russians to cancel the deal.