Defence officials in Seoul said what appeared to be two short-range ballistic missiles were fired at daybreak from near the northeastern city of Hamhung, flying 400 kilometres (250 miles) before splashing down in the sea.

It was the fifth round of launches in two weeks, with North Korean leader Kim Jong Un labelling them a "solemn warning" over the joint US-South Korean military drills.

"With the launching of two short range ballistic missiles today, a fifth such test in recent weeks, the Democratic People's Republic of Korea (DPRK) continues to undermine international work for building trust and establishing lasting peace and security on the Korean Peninsula, free of nuclear weapons," a spokesperson for the EU said in a statement.

"We expect the DPRK to refrain from any further provocations, abide by its stated commitments, and fully implement its international obligations as determined by multiple United Nations Security Council Resolutions."

The statement urged Pyongyang to take "concrete and credible" steps towards abandoning its nuclear and ballistic missile programmes and called for more talks.