The UK has refused to sign, ratify or be party to a treaty on the prohibition of nuclear weapons adopted by the United Nations on 7 July.
The Treaty on the Non-Proliferation of Nuclear Weapons (NPT) is aimed at preventing the spread of nuclear weapons and technology.
UN Secretary-General spokesman António Guterres said: “The impetus for the treaty reflects growing concerns over the risk posed by the continued existence of nuclear weapons, as well as awareness of the catastrophic humanitarian consequences that would result if nuclear weapons were ever used again.
“The treaty represents an important step and contribution towards the common aspiration of a world without nuclear weapons.
According to a statement from the UK Foreign and Commonwealth Office, the UK is committed to creating the conditions for a world without nuclear weapons.
However, it believes the NPT treaty fails to address issues that must be overcome to achieve lasting global nuclear disarmament.
The treaty will not improve the international security environment or increase trust and transparency, according to the statement.
To date, 191 states have joined the treaty, including five nuclear-weapon states.
The NPT has been ratified by more countries than any other arms limitation and disarmament agreement.
Additionally, the treaty establishes a safeguards system managed by the International Atomic Energy Agency (IAEA).