Russia has reiterated its warnings that Ukraine is ready to use a "dirty bomb'' and will bring the case to UN Security Council.

Iran PressEurope: A dirty bomb is a bomb that contains radioactive material, such as uranium, which is scattered through the air when its conventional explosive detonates.

It doesn't need to contain highly refined radioactive material, as is used in a nuclear bomb. Instead, it could use radioactive materials from hospitals, nuclear power stations or research laboratories.

This makes them much cheaper and quicker to make than nuclear weapons. They can also be carried in the back of a vehicle, for example.

Russia doubled down on a warning that Ukraine is preparing to use a "dirty bomb" on its own territory, a statement dismissed by the West and Kyiv as false, and was expected to bring the issue to the UN Security Council later on Tuesday.

Moscow sent a letter detailing its allegations about Kyiv to the United Nations late on Monday, and diplomats said Russia planned to raise the issue at a closed meeting with the Security Council on Tuesday.

"We will regard the use of the dirty bomb by the Kyiv regime as an act of nuclear terrorism," Russia's UN Ambassador Vassily Nebenzia told UN Secretary-General Antonio Guterres and the Security Council in the letter, seen by Reuters.

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