Hanoi, Jun 21 (IANS/DPA): Russian President Vladimir Putin has said South Korea would be making a "big mistake" if it supplies arms to Ukraine.

"If that happens, then we will make corresponding decisions that will not please the current leadership of South Korea," Putin said on Thursday during a trip to Vietnam.

The South Korean government had earlier expressed concern over a new Russia-North Korea strategic partnership that includes a vow of mutual aid if either country is attacked.

Seoul said the security commitments violated UN sanctions imposed on Pyongyang.

It also suggested it could reconsider its long-standing policy of not supplying weapons to Kiev.

North Korea, ruled by President Kim Jong Un, is subject to far-reaching UN sanctions and import bans due to its nuclear weapons programme, including the trade in weapons and the transfer of military technologies to the country.

During a state visit to Pyongyang on Wednesday, Putin signed the partnership agreement with Kim.

At a press conference in Hanoi on Thursday, Putin called Seoul's concerns unfounded.

He said South Korea had nothing to fear as the pact would only apply if either Russia or North Korea was attacked by a third country.

"As far as I know, (South Korea) is not planning any aggression" against North Korea, he said.

This means that "there is no need to fear our cooperation".

Putin also said that he would not deploy any North Korean soldiers in Ukraine.

However, he threatened to deliver high-precision weapons to North Korea as a response to Western arms deliveries to Ukraine.