Israel's foreign ministry is blocking the sale of unmanned air systems (UAS) to Ukraine, in a bid toavoid any negative impact on its relationship with Russia.

Since the armed conflict between pro-Russian separatists and Ukraine intensified, Kiev expressed its urgent need for some types of Israeli-made UAS.Negotiations began with Israeli manufacturers, and in at least one case reached an advanced stage.

The negotiations were conducted with the approval of the marketing process by the Israeli defence ministry, but when the time came to issue an export licence, the foreign ministry asked to freeze the process.

Senior Israeli sources say the step is a result of trying not to provoke Moscow.In recent years Israel has made an effort to persuade Moscow to avoid selling weapon systems and advanced surface-to-air missiles to Iran and Syria.