SEOUL, Oct 29 — North Korea fired an unknown projectile off its east coast on Thursday, Seoul's defence ministry said, less than a week after South Korea proposed talks over a growing border row.

Japan's defence ministry separately confirmed the launch of what it said "appears to be a ballistic missile".

"The North fired an unidentified projectile into the East Sea," South Korea's military said, referring to the body of water also known as the Sea of Japan.

Thursday's launch comes against the backdrop of growing tensions over a landmine explosion along the heavily fortified border between the two Koreas that saw three South Korean soldiers wounded.

A joint Seoul-UN investigation earlier this month concluded that North Korea had planted the landmines that exploded in the Demilitarised Zone (DMZ) more than a year ago, something Pyongyang has angrily denied.

Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, has blasted South Korean demands for an apology as "despicable" while separately rejecting an offer of medical equipment from Seoul.

The ratcheting tensions come as US President Donald Trump's recent overtures to Pyongyang have raised concerns that Seoul — an ally of Washington — could be sidelined in potential nuclear talks involving the North.

In October, North Korea launched several short-range ballistic missiles a day after Trump suggested he might meet with Kim Jong Un this year. — AFP