The Israeli prime minister, Benjamin Netanyahu, flies into Sochi on Thursday for talks with the Russian president, Vladimir Putin, that come after Moscow added its voice to criticism of his pre-election pledge to annex occupied Palestinian territories.

Netanyahu said on Tuesday that he would annex up to a third of the West Bank if he is re-elected in next week’s parliamentary polls. His announcement was condemned by the Palestinians, Arab countries, the UN and the EU.

The Russian foreign ministry said on Wednesday that Netanyahu’s move could “lead to a sharp escalation of tension in the region and undermine hopes for the establishment of a long-awaited peace between Israel and its Arab neighbours”. The Kremlin has not yet commented.

The meeting in Sochi, on Russia’s Black Sea coast, is the third between Netanyahu and Putin this year. They also held talks ahead of Israeli elections in April. The two leaders have met more than a dozen times since 2015.

Netanyahu and Putin are also due to discuss the conflict in Syria. Russia has backed the Syrian leader, Bashar al-Assad, while Israel has conducted hundreds of strikes in the country, most of them against what it says are Iranian and Hezbollah targets. Both Iran and Hezbollah, a Lebanese Shia group, support Assad.

Netanyahu told Russia’s RBC media outlet that his good relationship with Putin had helped avert “a near-unavoidable clash” between the Israeli and Russian militaries in Syria. The two countries signed a deal in 2015 to coordinate their military action in Syria to avoid accidentally trading fire.

Russian media reports said this week that Su-35 fighter jets had prevented Israeli warplanes from carrying out airstrikes in southern Syria. The incident came after Iranian-backed forces were reported to have launched a rocket attack on Israel.

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Putin is due to meet the Iranian president, Hassan Rouhani, and the Turkish president, Recep Tayyip Erdoğan, in Ankara next week to discuss the Syria conflict. Russia offered to help Iran dodge US sanctions last month by allowing Tehran to transport crude oil through its ports in Crimea, which Russia seized from Ukraine in 2014.

Netanyahu sought to dissuade Russia from closer ties with Iran, telling RBC that Tehran posed a threat not only to Israel and the west, but also to Moscow.

Netanayhu’s visit to Russia was interpreted at home as a last-minute attempt to win over Russia-speaking Israelis in next Tuesday’s election. He has launched an aggressive campaign to woo the minority of a million people, running ads in Russian and erecting a giant poster of himself and Putin on his Likud party’s Tel Aviv headquarters.

The prime minister wants to steal voters from his ally-turned-rival, Avigdor Lieberman, himself an immigrant from the Soviet Union. He is widely predicted to win enough seats to become Israel’s kingmaker next week, and possibly end Netanyahu’s 13-year career in high office.

Lieberman, a hardline secular ultranationalist, has denounced Netanyahu as weak on security and for making deals with religious parties. The 61-year-old former defence minister refused to join Likud’s previous coalition in May, shattering Netanyahu’s attempts to form a government and precipitating next week’s repeat poll.

Netanyahu has also sought to appeal to far-right religious and nationalist voters who fear the political influence of Palestinian citizens of Israel. On Thursday Facebook suspended a chatbot on Netanyahu’s official page after it breached hate speech policy by sending visitors a message warning of Arabs who “want to destroy us all”.