Israeli Prime Minister Benjamin Netanyahu is to hold talks on Tuesday with Russian President Vladimir Putin on the conflict in Syria, the Kremlin said, amid concerns Moscow plans to deliver advanced missiles to the Damascus regime.

"During the meeting an exchange of opinion is planned on key aspects of bilateral ties," the Kremlin said in a statement.

"It is expected that major attention will be paid to the current situation in the Middle East, first and foremost in Syria," the statement said.

It said the talks would take place in Russia, without giving further details.

Netanyahu is expected to call on Putin at his Black Sea residence in Sochi as the casualty toll in Syria climbs to more than 80,000 people amid persisting signs that the West and Russia do not see eye to eye on Syria despite recent pledges to try to overcome differences.

The Wall Street Journal reported last week that Israel had provided information to Washington about the imminent sale to Syria of Russian S-300 missile batteries, advanced ground-to-air weapons that can take out aircraft or guided missiles.

The weapons would significantly strengthen Syria's defences and complicate any foreign military intervention.

Netanyahu will travel to Russia after Israel twice earlier this month carried out air strikes near Damascus, attacks a senior Israeli source said were aimed at preventing the transfer of sophisticated weapons to Hezbollah, the powerful Lebanese Shiite group allied to Syria.

Russia last week refused to rule out supplying weapons to Syria, saying it has to honour existing contracts.

British Prime Minister David Cameron, who paid a rare visit to Putin's Sochi residence on Friday to discuss strategy on Syria, is believed to have also raised the issue of Russian arms supplies to the Damascus regime during talks with Putin.

"Vladimir Putin assured his British colleague that the S-300 complexes will be delivered to Syria for sure," wrote the Kommersant daily on Monday.

On a visit to Warsaw on Friday, Foreign Minister Sergei Lavrov said Moscow was continuing to fulfil contracts by delivering military hardware to Assad's regime in defiance of calls for a freeze.

"Russia has sold and signed contracts a long time ago, and is completing supplies of the equipment, which is anti-aircraft systems, according to the already signed contracts," he said on Friday.

Kommersant also said, citing a source who participated in Lavrov's meeting with his German and Polish counterparts Guido Westerwelle and Radoslaw Sikorski, that the contract under question dated back to 2010.

"Part of the equipment has been sent to Syria, while another part is indeed being prepared to be shipped," Kommersant said.

A high-ranking diplomatic source, who participated in the Putin-Cameron talks, told Russian news agencies over the weekend that Russia had an obligation to implement it arms contracts.

"Everything is clear here: there is no embargo on supplies, and we are implementing contracts signed earlier, that is we are fulfilling obligations we have taken upon ourselves," the source said, adding the arms were defensive.

After the attacks by the Israeli air force on Syria "it would be hard for Netanyahu to convince the Russian president not to supply defensive weapons," said Boris Dolgov, of the Center of Arabic and Islamic Studies at the Russian Academy of Sciences.

The Jewish state has repeatedly warned it will intervene to prevent the transfer of advanced weaponry to Hezbollah, with which it fought a devastating 2006 war.

The West and Russia have been repeatedly at odds over the Syria conflict, with the United States and Europe accusing Moscow of seeking to prop up Assad and selling him arms.