This handout photograph taken and released by the Ukrainian Presidential Press Service on Monday shows Ukraine's President Volodymyr Zelensky inspecting the construction of fortifications at an undisclosed location in Donetsk region, amid the Russian invasion of Ukraine. (AFP-Yonhap)

The number of North Korean troops stationed inside Russia could grow to 100,000, Ukrainian President Volodymyr Zelenskiy said on Tuesday.

Kyiv and its Western allies say North Korea has supplied Russia with weaponry and troops to bolster its full-scale invasion of Ukraine.

"Now, Putin has brought 11,000 North Korean troops to Ukraine's borders. This contingent may grow to 100,000," Zelenskiy said in a virtual address to the European Parliament.

South Korea's spy agency said last week that North Korean troops had already engaged in combat operations against Ukrainian forces.

Russian President Vladimir Putin signed a treaty into law this month on strategic partnership with North Korea, which includes a mutual defense provision. (Reuters)