Britain has announced for the first time the size of its nuclear arsenal, saying it has 225 warheads.

Foreign Secretary William Hague told parliament Wednesday that the time is right to re-examine Britain's policy on the use of nuclear weapons.  Hague said he hopes his announcement will help build trust between nuclear and non-nuclear weapons states, and contribute to efforts to reduce the number of nuclear weapons worldwide.

Britain had earlier revealed it had 160 operational warheads, but Hague's comments are the first time the maximum size of the total stockpile was made public.

The announcement by the new British government follows the Obama administration's disclosure earlier this month of the size of the U.S. nuclear weapons stockpile.  It also coincides with a major nuclear non-proliferation conference at the United Nations in New York.

The Pentagon announced three weeks ago that the U.S. had 5,113 nuclear warheads in its stockpile as of last September.  U.S. defense officials said the number represents a significant drop from the 31,000 warheads that were in the U.S. inventory in 1967, during the Cold War era.

The Pentagon's announcement followed an April meeting in Prague between U.S. President Barack Obama and Russian President Dmitri Medvedev.  The two leaders signed a treaty that cuts each country's nuclear arsenal by about 30 percent.   

The U.S. Senate and Russia's parliament must ratify the treaty in order for it to take effect.  

The treaty would replace the 1991 Strategic Arms Reduction Treaty, which expired last year.

The new treaty would allow each country to maintain about 1,500 strategic nuclear weapons.

Some information for this report was provided by AP and Reuters.