Seoul - (AFP) - North Korea fired an unidentified ballistic missile Friday towards the sea, Yonhap news agency quoted the South Korean army as saying.

This new ballistic experiment comes a day after Pyongyang announced that it had launched two long-range strategic cruise missiles, in an experiment personally supervised by leader Kim Jong Un.

Pyongyang described its recent missile tests as tactical nuclear exercises simulating control of airports and military facilities in South Korea.

Yonhap quoted the South Korean Joint Chiefs of Staff as saying that it detected the missile launch from the Sunan area in Pyongyang in the early hours of Friday morning.

The Chiefs of Staff did not mention other details about the missile, noting, on the other hand, that "our army maintains a state of complete readiness in close cooperation with the United States."

About two hours before monitoring the ballistic missile launch, Yonhap reported, quoting the Chief of Staff, that about 12 North Korean warplanes flew close to the border with South Korea, which prompted Seoul to send fighters to intercept them, including F-35A fighters.

This is the second incident between the two countries within one week involving fighter jets.

These developments come amid escalating military tensions on the peninsula following a series of weapons tests conducted by Pyongyang.

And the Yonhap news agency quoted the Chief of the Joint Staff of South Korea as saying that 10 fighters were detected while flying 25 km north of the border between the two Koreas, between 22:30 Thursday night and 00:20 Friday morning local time, crossing the line that is automatically activated in response from the South.

Seoul has sent military aircraft, including the F-35A fighter jet, Yonhap quoted the Joint Chiefs of Staff as saying.

For its part, North Korea accused Seoul on Friday (local time) of carrying out a "provocative act" near their common border and said that the South Korean army was "provoking military tension", according to state media.

A North Korean army spokesman said in a statement that the South Korean army Thursday fired "artillery fire for about ten hours near the advanced defense area of the Fifth Corps of the Korean People's Army."

He added that the North Korean army "took strong military countermeasures" in response to the "provocative act".

According to the official information agency in Pyongyang, the Korean People's Army "is issuing a stern warning to the South Korean army, which is recklessly stirring up military tension in the frontline area."

In Washington, the US State Department condemned the new North Korean ballistic missile test.

A spokesman for the ministry said, "This experiment, along with others that took place over the past month, violates many UN Security Council resolutions" and "threatens peace and stability in the region."

The US State Department spokesman regretted that North Korea "refuses to respond" to the offers of dialogue sent to it by the United States.

Earlier this week, Kim rejected the idea of resuming talks on banned weapons programmes, saying his country "doesn't feel the need to do so".

In turn, the French Foreign Ministry said in a statement that "France deals with grave concern with North Korea's statements on October 13, in which it confirmed that it had launched long-range strategic missiles that could carry tactical nuclear weapons."

"These statements, coupled with the North Korean military provocations in the north of the Demilitarized Zone, contribute to an alarming growth in tension on the peninsula," the State Department added.

Paris urged "North Korea once again to fulfill without delay its international obligations, return to the negotiating table and put an immediate end to its destabilizing steps."