China's top diplomat Wang Yi met with Russia's deputy foreign minister in Beijing on Wednesday to discuss the Ukraine crisis, amid Western condemnation of Moscow's closer ties with North Korea.

Wang told Andrey Rudenko that China's relationship with Russia was "inevitable" and "strong," adding it was "not affected by the changing international situation, and is not directed at or affected by third parties," according to a statement.

Tensions have escalated in recent weeks as the United States and South Korea have slammed the apparent presence of North Korean troops in Russia.

And Wednesday's meeting between Wang and Rudenko came as North Korean Foreign Minister Choe Son Hui was due to meet with his Russian counterpart Sergei Lavrov in Moscow.

South Korea, NATO and the United States claim thousands of North Korean troops are training in Russia – which Moscow and Pyongyang deny.

The first batch of elite forces left for eastern Russia's Vladivostok in early October, according to Seoul's spy agency.

The roughly 10,000 North Korean soldiers sent to train "will probably augment Russian forces near Ukraine over the next several weeks," Deputy Pentagon Press Secretary Sabrina Singh told journalists this week.

While Pyongyang denies its troops are training in Russia, North Korea's vice foreign minister, Kim Jong Gyu, said that were such a deployment to happen, it would be in line with international law.

China considers both Russia and North Korea its close partners.

The U.S. government has expressed with China its concerns over Pyongyang's deepening military engagement.

When asked about talks with Washington during a regular news conference Wednesday, China's foreign ministry declined to comment.

The foreign ministry also declined to confirm whether Wang raised the issue of North Korean troops in Russia with Rudenko when they met.