Updated

Iran's foreign ministry says the country is a committed signatory to the Nuclear Non-Proliferation Treaty and will continue cooperating with the U.N. nuclear watchdog agency.

Five major powers on Friday labeled Iran and North Korea as "serious challenges" to the world's nuclear security, saying they have defied U.N. sanctions. They cited Iran's "continued pursuit of certain nuclear activities" as among the biggest threats to the treaty, the world's most important pact on preventing the spread of nuclear arms.

Responding to the charge, the semi-official ISNA news agency on Saturday quoted Iran foreign ministry spokesman Ramin Mehmanparast as saying that Iran is "loyal" to its commitments under the treaty and will continue working with the International Atomic Energy Agency.

The West suspects Iran is pursuing nuclear weapon, a charge Tehran denies.