Japan's Prime Minister Shinzo Abe has vowed his country will strive to achieve a "world without nuclear weapons".

The leader made the remarks on Sunday (6 August), during commemorations to mark the 72nd anniversary since the first atomic bomb was used.

During Wolrd War II, the US dropped an atomic bomb on the Japanese cities of Hiroshima, killing at least 126,00 people. Some of whom died instantly, while others throughout the year, due to long-term effects of the bombing.

Three days later, another bomb was dropped on the city of Nagasaki, killing between 60,000 and 80,000 people instantly.

"Here in Hiroshima city, I renew my pledge to do my utmost to bring about a nuclear free world and eternal peace. And I also pray for the peace of the atomic bomb victims and the bereaved families, those attending here as well as the citizens of Hiroshima city," Abe said, according to Reuters.

Marking the anniversary, UN Secretary General António Guterres said the world is still far from ridding itself of nuclear weapons.

"The states possessing nuclear weapons have a special responsibility to undertake concrete and irreversible steps in nuclear disarmament," he said, adding that there are still 15,000 nuclear weapons in the world.

"Last month, Member States of the United Nations adopted the Treaty on the Prohibition of Nuclear Weapons. This measure is the result of a global campaign focused on the unacceptability of the use of nuclear weapons under any circumstances. Yet our dream of a world free of nuclear weapons remains far from reality," Guterres continued.

The Hiroshima anniversary came as tensions are increasing in Asia, over North Korea's repeated refusals to stop testing missiles and nuclear weapons, prompting the UN to apply a fresh round of economic sanctions on the country.

On Saturday, 5 August, the organisations' Security Council unanimously approved a US-drafted resolution that imposes economic sanctions targeting the exports of seafood, coal, iron ore, iron, lead and lead ore. It also calls for capping the number of North Korean workers allowed overseas.

In response, Pyongyang warned the US would turn into a "sea of fire".

Abe has been pressurised to sign the UN treaty on nuclear weapons. However, he declined to do so, arguing that a unilateral disarmament by Japanese allies would help North Korea and China.

"We need a realistic, step-by-step approach in order to achieve a nuclear-free world"Abe said on Sunday, according to the New York Times.

Nagasaki Hiroshima anniversaries
A woman prays at the Hiroshima Peace Memorial ahead of the Hiroshima Peace Memorial Ceremony at Hiroshima Peace Memorial Park in Hiroshima Yuya Shino/ Getty Images