North Korea is developing its nuclear and missile capabilities at an "unprecedented" pace in a "real and obvious threat", the South has warned.

Seoul claims a US anti-missile defence system agreed with Washington last year needs to be deployed in its country without delay despite objections from China.

South Korea and America say the Terminal High Altitude Area Defence (THAAD) is designed to protect against a growing nuclear threat from Kim Jong-Un's North.

But China says THAAD's powerful radar could penetrate its own territory, leading to calls from some South Korean opposition leaders to delay or cancel its deployment.

Meanwhile, President Donald Trump's administration has announced plans to develop a "state-of-the-art" missile defence system to protect the US against attacks from Iran and North Korea.


Image: Mr Trump's administration announced plans for a missile defence system

The statement, posted on the White House website, did not provide details on whether the system would differ from those already under development, its cost or how it would be paid for.

The policy announcement came a day after reports that Pyongyang was readying a test of an upgraded intercontinental ballistic missile prototype.

North Korea: Credible threat?

According to South Korean agency Yonhap, news of the test appeared to have been intentionally leaked by North Korea to send a "strategic message" to Mr Trump.

Pyongyang carried out two nuclear tests and fired multiple ballistic missiles in 2016 - an average of two a month - despite UN sanctions, according to the South's acting president Hwang Kyo-Ahn.

Image: Acting South Korean president Hwang Kyo-Ahn has hit out at Pyongyang's nuclear tests

He said: "Its nuclear and missile capabilities are developing at an unprecedented pace. They are a real and obvious threat. They are also miniaturising nuclear weapons."

A "swift" deployment of the THAAD system "is necessary to protect the lives and safety of our people", he added.

But some opposition candidates have pledged to scrap the agreement if they win a presidential election due this year.

The North and South are technically still at war because their 1950-53 conflict ended in a truce, not a peace treaty.

Image: Mr Kim watches a ballistic rocket launch drill

The missile defence plan has led to anger in Beijing, which has imposed a series of measures seen as economic retaliation in the South.

They include effectively barring K-pop stars from performing on the Chinese mainland and not authorising South Korean airlines to operate charter flights between the countries.

Prime Minister Mr Hwang said there were "some concerns" about Bejing's response to THAAD and that more time was needed to tackle these issues.

South Koreans celebrate president's impeachment

He added: "The relationship between South Korea and China was not made in a day. We have engaged in diverse cooperation since the beginning of our diplomatic ties."

He was speaking as president Park Geun-hye has been impeached by parliament amid a corruption scandal and stripped of her powers as she awaits a court decision on her fate.