Meanwhile, the AFP news agency has issued a warning that a still image of the missiles being launched, one of several distributed by Iran, was "apparently digitally altered".
The photograph, published on the Iranian Revolutionary Guards website and reproduced by media organisations - including the BBC News website - showed four missiles taking off from a desert launch-pad.
But a similar image, issued by the Associated Press, shows one of the missiles still in its launcher after apparently failing to fire.
The BBC News website's picture editor, Phil Coomes, said: "Having examined the photograph from AFP, it can be seen that parts have been edited, with smoke trails and parts of the foreground being cloned."
In recent weeks, both Israel and Iran have been testing and showing off their military hardware, each saying that in the event of provocation it is more than capable of defending itself.
The Israeli air force recently carried out a large-scale exercise over the Mediterranean - regarded by many observers as a dress rehearsal should the order be given to attack Iran's nuclear facilities. Israel believes Iran is building nuclear weapons, although Tehran insists its nuclear programme is purely for civilian energy.
Western leaders have been trying to convince Iran to stop enriching uranium, which it has continued doing despite sanctions from the UN and the European Union.
Iran test-fires missiles in the Gulf - footage from Iranian state TV
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