MOSCOW (Reuters) - Pyongyang does not plan to hold any talks with Washington about its nuclear program, a senior North Korean diplomat said on Friday, declaring that possessing nuclear weapons was a matter of life and death for North Korea, the RIA news agency reported.

Tension has soared on the peninsula following a series of weapons tests by North Korea and a string of increasingly bellicose exchanges between U.S. President Donald Trump and North Korean leader Kim Jong Un.

Trump, in a speech last month at the United Nations, threatened to "totally destroy" North Korea if necessary to defend itself and allies and called the North's leader a "rocket man" on a suicide mission.

Choe Son-hui, director-general of the North American department of North Korea's foreign ministry, told a non-proliferation conference in Moscow Washington would "have to put up" with North Korea's nuclear status, RIA reported.

"This is a matter of life and death for us. The current situation deepens our understanding that we need nuclear weapons to repel a potential attack."

"We will respond to fire with fire."

Pyongyang would regard any attempts to strangle the country via U.N. Security Council sanctions as an attempt "to declare war".

Russian Foreign Minister Sergei Lavrov, addressing the same conference earlier on Friday, urged world powers to get behind a joint Russian-Chinese roadmap for settling the crisis over North Korea's weapons program.

"We are convinced that its implementation will promote the lessening of military activity and tension on the Korean peninsula and the forming in Northeastern Asia of a system of equal and indivisible security," he said.

The plan proposes a moratorium on North Korea's missile and nuclear weapons tests, while South Korea and the United States suspend holding military exercises.

"The main task at the current stage is to prevent a military conflict which will inevitably lead to a large-scale humanitarian, economic and ecological catastrophe," Lavrov said. "All the sides involved should exercise restraint."

(Reporting by Dmitry Solovyov; Editing by Ralph Boulton)