Washington, Sep 3 (IANS): Iran's civilian nuclear programme may be legitimised under international law, reinforced by a deal reached with world powers on July 14, but Iran's efforts to weaponise that programme will forever be illegitimate under the deal, US Secretary of State John Kerry said on Wednesday.

Kerry delivered a speech in Philadelphia within hours of Democrat Senator Barbara Mikulski of Maryland announcing her intentions to support the deal, CNN reported.

Her endorsement provides the Obama administration with the support necessary to preserve the accord through a vote on the deal scheduled for later this month.

The agreement, Kerry noted, provides the International Atomic Energy Agency with the ability to "go wherever the evidence leads," including to undeclared facilities such as military installations.

He said the agreement is permanent, in that Iran is forever bound to keep its nuclear programme exclusively peaceful.

A signatory of the Nuclear Non-Proliferation Treaty since 1968, Iran was allowed to retain a peaceful nuclear programme and has, since that time, committed not to pursue nuclear weapons.

Kerry also noted that if Iran wanted to deceive the international community, it would have to construct an entirely secret chain of evidence to cheat. "Iran could never get away with such a deception," he said.