The New York Times says North Korean leader Kim Jong Un plans to travel to Russia to discuss with President Vladimir Putin the possibility of the North supplying weapons to Russia.

Citing senior US officials and other sources, the newspaper reported on Monday that Kim plans to travel to Vladivostok later this month, likely by train.

Kim and Putin are expected to attend the Eastern Economic Forum, which is scheduled to run from September 10 to 13 in the Far Eastern Russian city.

In apparent preparations for Kim's trip, about 20 North Korean officials, including some who oversee leadership security protocol, reportedly traveled from Pyongyang to Vladivostok by train, then flew to Moscow, in August.

The newspaper quoted the sources as saying "Putin wants Kim to agree to send Russia artillery shells and antitank missiles."

They also said "Kim would like Russia to provide North Korea with advanced technology for satellites and nuclear-powered submarines" and "Kim is also seeking food aid."

A White House spokesperson said last Wednesday that Kim and Putin had exchanged letters, pledging to increase bilateral cooperation.

White House National Security Council spokesperson John Kirby expressed concerns that Russia and North Korea have been negotiating a possible arms deal.