President Yoon Suk Yeol gives a speech at the 78th United Nations General Assembly held at the United Nations Headquarters in New York on Wednesday. (Yonhap)

President Yoon Suk Yeol criticized a recent talk between leaders of Russia and North Korea that a potential arms trade between them would be a "direct provocation" not only to Ukraine but also to South Korea, stressing that Seoul won't just sit and watch.

"If the DPRK acquires the information and technology necessary to enhance its (weapons of mass destruction) capabilities in exchange for supporting Russia with conventional weapons, such a deal between Russia and the DPRK will be a direct provocation threatening the peace and security of not only Ukraine but also the Republic of Korea," he said in his second UN address delivered in New York on Wednesday.

"The Republic of Korea, together with its allies and partners, will not stand idly by."

The South Korean leader also said Russia was deserting its role as a permanent member of the UN Security Council to wage a war against Ukraine and it is "paradoxical" for Moscow to receive arms supply from a regime which has been defying a resolution it signed to.

“In such a situation, the call to reform the UN Security Council would receive broad support,” he said.

His remarks on the Security Council reform align with previous statements made by US President Joe Biden and Japanese Prime Minister Fumio Kishida at the UN. Biden expressed US support for expanding the council to include a greater number of permanent and nonpermanent members. Kishida accused permanent members Russia and China of violating international law.

The council is composed of five permanent members -- the US, Russia, China, France and Britain -- each holding veto power. A growing number of countries are advocating for a broader and more equitable representation within the council.

Yoon called on the international community to “unite” in unwavering solidarity and steadfastly adhere to principles to “deter any unlawful provocation.”

Hours later, the Russian Embassy in South Korea said on its Facebook page that Yoon's remarks "cause deep regret." The embassy accused Yoon of joining a propaganda effort started by Washington and echoed by US and South Korean media to discredit Russia-North Korea collaboration.

The embassy said it views such unfounded statements, made in what it called the "best" traditions of "megaphone" diplomacy and reminiscent of the controversial "vial" presentation by former US Secretary of State Colin Powell, as provocative and confrontational.

While President Yoon Suk Yeol delivers a keynote speech at the 78th United Nations General Assembly held at the United Nations Headquarters in New York on Wednesday (local time), the seats for the North Korean delegation are empty and officials from China take note.

“We call on the leadership of the Republic of Korea, with which Russia has solid experience of mutually beneficial communication and cooperation, to base their actions on a sober and objective assessment of the current situation,” the embassy said.

Despite the calls from Korea and its allies and partners, it appears to be difficult for the UN to come up with a fresh set of sanctions or a joint response plan against the military cooperation between North Korea and Russia, according to observers.

While China and Russia continue to reject resolutions on additional sanctions against North Korea or the war in Ukraine, only Biden among the council's five permanent members attended the general meeting this week. Leaders from China, Russia, France and the UK were all absent.

Yoon's speech did not mention China, which observers say Seoul could have considered a trilateral summit with China and Japan to be held later this year.

On Ukraine, Yoon also vowed to implement a comprehensive support program that encompasses security, humanitarian assistance and reconstruction in line with Korea’s commitment to the “Ukraine Peace and Solidarity Initiative.”

Two weeks ago at the G-20 Summit, he pledged that Korea would support Ukraine’s reconstruction by providing $300 million next year, and a mid- to long-term support package exceeding $2 billion.

Yoon noted that Seoul will expand its support to narrow existing gaps in development, climate and the digital sphere, despite the government's fiscal austerity measures this year.

The Korean government has increased the Official Development Assistance budget plan for the upcoming year by over 40 percent.

He announced that Korea would contribute an additional $300 million to the Green Climate Fund and initiate a "Carbon Free Alliance," an open platform that anyone in the world can join to promote the adoption of carbon-free energy. Additionally, he mentioned imminent plans to introduce a Digital Bill of Rights to foster a desirable future in the digital realm.