North Korea fired about 10 short-range ballistic missiles from its east coast into the Sea of Japan, South Korea's Joint Chiefs of Staff (JCS) said on Thursday. The launch came less than a week after Seoul proposed talks to ease a growing dispute along the border.

According to the JCS, the missiles were launched at about 12:30pm local time (03:30 GMT) from an area around Wonsan on the North's eastern coast. Japan's Defence Ministry separately confirmed a launch of what it said could be a ballistic missile, which fell outside Japan's Exclusive Economic Zone, Tokyo-based Kyodo News reported.

The launch follows rising tension over a landmine explosion on September 21 that injured three South Korean soldiers in the Demilitarized Zone (DMZ), the heavily fortified border between the two Koreas. A joint investigation by South Korea and the United Nations earlier this month concluded that North Korea had planted the mines more than a year ago. Seoul has called on Pyongyang to apologise.

North Korea has rejected those findings. This week it sent a letter to the UN Security Council accusing South Korea of fabricating the explosion. Kim Song, North Korea's permanent representative to the UN, described the claims as a "farce to evade the responsibility for the ever-escalating tensions on the Korean peninsula." He also criticised what he called the "provocation the ROK [Republic of Korea] committed by groundlessly shifting the blame" for the "dubious 'mine explosion incident'", and warned that violations of his country's sovereignty could trigger self-defence.

Kim Yo Jong, the influential sister of North Korean leader Kim Jong Un, called South Korea's demands for an apology "despicable". She also separately turned down an offer of medical equipment from Seoul.

South Korea has sought to calm the situation. Last Friday it said it had invited the North to military talks aimed at restoring communication channels, as military activity along the border has increased. It is unclear whether Pyongyang will accept. Kim Jong Un has taken a hardline stance toward Seoul and in recent years has suspended almost all dialogue and cooperation with the South.

The escalation also unfolds amid concern in Seoul about its position in possible diplomacy with the North. Recent overtures from US President Donald Trump to Pyongyang have raised fears that South Korea, a US ally, could be sidelined in any nuclear talks involving North Korea.

Pyongyang has launched missiles at sensitive diplomatic moments before. It fired several short-range ballistic missiles a day after Trump suggested he might meet Kim this year.