Russia plans to start up a nuclear reactor at Iran's Bushehr plant by the end of the year, the head of Russia's state nuclear corporation said on Thursday.

"It is difficult to say how much time it will take to create the bases for our fleet in these countries, but within a few years this will be done without question," the official was quoted as saying. "The political decision on this question has been taken," the official said.

Israel has begun a diplomatic effort to justify its threats to launch a military response to rocket attacks launched on its villages from the Hamas-ruled Gaza Strip.

Russia reassured Israel on Sunday that it stands by its commitment not to supply Iran with advanced S-300 anti-aircraft missiles despite an Iranian lawmaker's statement that the system "is being delivered to Iran."