U.N. Secretary-General Ban Ki-moon on Thursday welcomed the signing of a historic nuclear arms treaty between the United States and Russia.

The signing of the New START Treaty, Ban said, was "an important milestone in international efforts to advance nuclear disarmament and to achieve a world free of nuclear weapons."

"The secretary-general welcomes the signing of the New START Treaty as an important milestone in the international efforts to advance nuclear disarmament and to achieve a world free of nuclear weapons," Ban said in a statement.

U.S. President Barack Obama and Russian President Dmitry Medvedev signed the landmark nuclear arms treaty on Thursday, committing to significant reductions in their countries' atomic arsenals.

The pact was signed at Prague Castle, the seat of Czech presidents. At a news conference following the signing, Obama hailed the "historic" treaty as one step toward the realization of his dream of a nuclear-free world, which he outlined during a speech in Prague on April 5 last year.

"The secretary-general commends President Medvedev and President Obama for their leadership," the U.N. statement said. "He believes that this significant achievement will also help create a positive atmosphere for the upcoming Review Conference of the Parties to the Treaty on the Non-Proliferation of Nuclear Weapons."

The review conference will be convened in May at the U.N. Headquarters in New York.

"The secretary-general hopes that the Russian Federation and the United States continue their efforts in the pursuit of the reduction and elimination of all nuclear weapons," the statement added.