Russian President Vladimir Putin and Israeli Prime Minister Benjamin Netanyahu were set Tuesday to hold talks on the conflict in Syria amid growing concern about Moscow's arms deliveries to the Damascus regime while the death toll spirals.
Netanyahu is just the latest world leader to beat a path to Putin's door for talks on Syria in recent days, after US Secretary of State John Kerry and British Prime Minister David Cameron met the Russian strongman last week.
In the wake of the talks with Netanyahu at Putin's vacation residence in the southern resort of Sochi, UN Secretary General Ban Ki-moon is also due to travel to Russia later this week.
"The situation (in Syria) unfortunately has a tendency towards a further escalation which can only arouse great concern on the part of Russia... and Israel," Putin's spokesman Dmitry Peskov said ahead of the talks with Netanyahu, quoted by Russian news agencies.
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 President Bashar al-Assad and supplying his regime with military hardware.
The flurry of diplomatic activity indicates some hope on the part of the West that Russia could be persuaded to soften its line over a conflict that according to activists has now killed over 80,000 people.
The West and Israel are particularly concerned about Russia's refusal to rule out further deliveries to Syria of advanced S-300 missile batteries under an existing contract.
Netanyahu is expected to emphatically warn Putin against delivering such weaponry which would severely complicate any future air attacks against the Assad regime.
Putin has over the last years worked to improve relations with Israel -- now home to a large Russian-speaking community -- after tetchy ties in the Soviet era when Moscow was perceived as stanchly pro-Arab.
The date of Netanyahu's trip was only announced on Monday by the Kremlin and it is not clear how far it was planned in advance.
The issues to be discussed have some parallels to a trip Netanyahu made to Moscow in September 2009 for Kremlin talks deemed so sensitive that the visit was kept secret at the time.
According to Israeli media, Netanyahu is believed on that trip to have raised fears about a Russian plan to deliver S-300s to Iran that Moscow decided in the end not to fulfil.
But Russian Foreign Minister Sergei Lavrov said last week that Moscow was "completing" supplies of equipment to Syria agreed under previous contracts that were completely legal.
According to the Wall Street Journal, citing an Israeli intelligence report, the 2010 contract with Syria includes six launchers and 144 missiles, each with a range of 125 miles (200 kilometres).
Cameron said on Monday after talks with US President Barack Obama that London and Moscow had found "common ground" on the crisis. Obama agreed, saying Russia had an "interest as well as an obligation" to work on resolving the crisis.
Particular hope has focussed on the agreement between Russia and the United States reached during Kerry's visit to work to convene an international peace conference on Syria.
The conference is likely to be held in early June and not this month as the US works to bring the sides together, State Department spokeswoman Jen Psaki said Monday.
According to the RIA Novosti news agency, Lavrov will hold a repeat meeting with Kerry over the plans for the Syria conference on the sidelines of a forum on the Arctic in Sweden this week.
Peskov meanwhile said it would be premature to speculate on the possible participation of Putin in the Syria conference, saying this would depend on the format and level of the event.