A U.N.-adopted nuclear ban treaty is likely to enter into force early next year as the number of signatories is anticipated to reach the needed threshold of 50 soon, possibly later this month, a diplomatic source said Friday.

According to the source and the International Campaign to Abolish Nuclear Weapons, or ICAN, 46 countries and regions have completed ratification procedures.

Photo taken in September 2018 shows the United Nations flag in New York. (Getty/Kyodo)

The Treaty on the Prohibition of Nuclear Weapons, adopted in 2017, will enter into force 90 days after it has been ratified by at least 50 countries and regions.

At least four additional countries have already notified the United Nations of their intention to ratify the treaty, the source and the nonprofit organization said, without revealing the names of any such signatories.

U.N. Secretary General Antonio Guterres said at a meeting of the General Assembly on Friday, "The only way to completely eliminate nuclear risk is to completely eliminate nuclear weapons" and that the nuclear ban treaty "remains the cornerstone of the nuclear disarmament and nonproliferation regime."

"I look forward to the entry into force of the Treaty on the Prohibition of Nuclear Weapons, which reflects the desire of a large number of States to free the world of the threat," he added.

U.N. Secretary General Antonio Guterres is shown during an online interview on Sept. 9, 2020. (Photo courtesy of the United Nations)(Kyodo)

While the entry into force of the pact will likely be welcomed by antinuclear activists as well as survivors and relatives of victims of the atomic bombings of Hiroshima and Nagasaki, the treaty's effectiveness remains uncertain.

The five permanent members of the U.N. Security Council -- Britain, China, France, Russia and the United States, all of which are nuclear powers -- have declined to ratify the pact.

Japan, the only country in the world to have experienced nuclear bombings, as well as Germany, have not ratified the pact either, in light of their security alliances with the United States providing nuclear deterrence against adversaries.

Many of the 46 signatories of the nuclear ban pact are small countries in Africa, Asia, Latin America and Oceania.