Leaders of South Korea and Britain have called for joint efforts to denuclearize North Korea and to expand their bilateral trade, the Seoul government said Friday.

South Korean President Moon Jae-in also asked for Britain's support in dismantling his country's aged nuclear reactors, according to Moon's presidential office Cheong Wa Dae.

Moon's remarks came in a telephone conversation with British Prime Minister Theresa May.

"President Moon Jae-in noted Britain was a close ally, which had dispatched the second-largest contingent of troops to South Korea during the (1950-53) Korean War after the United States, and where the largest number of South Korean expats currently live in Europe," the office said in a press release.

"Also noting Britain was South Korea's second-largest partner among all European countries in terms of trade and investment, the president said he hoped the countries' close economic relationship will not be affected by Britain's exit from the European Union and continue to develop," it added.

May, too, expressed her wish to expand her country's trade relations with South Korea, especially in preparation for Brexit, according to Cheong Wa Dae.

The British premier was the latest in a series of foreign leaders to call Moon following his win in a rare presidential by-election held Tuesday.

The new South Korean president was inaugurated only one day after the election as the event sought to fill the top elected office, which became vacant after former President Park Geun-hye was removed on March 10 over a range of corruption allegations.

Turning to global issues, Moon asked for Britain's support in denuclearizing North Korea.

May quickly agreed to help, also promising to share her country's experience in ending Iran's nuclear ambitions, according to the presidential office.

Moon then turned to nuclear issues in his own country, which is moving to dismantle its first and thus oldest nuclear reactor, Kori Reactor 1.

"The president said he hoped the countries' cooperation in the nuclear sector will also be enhanced, noting Britain possessed advanced technologies and years or experience related to dismantling nuclear reactors," the press release said.

The decision to shut down and dismantle the Kori reactor was made under the former administration with the process set to begin next month.

Moon, however, has vowed to shut down other aged reactors as well, including Wolsong Reactor 1, that had its operation permit extended in 2015 to 2022. (Yonhap)