SEOUL (AFP) - North Korea said on Friday (Oct 27) it would free a South Korean fishing crew and their boat in a rare humanitarian gesture amid high tension on the peninsula.

"391Hungjin" and its crew were captured off the North's east coast on Saturday when it "illegally intruded into waters... under the control of the DPRK side," state-run news agency KCNA said, using the North's official name.

The crew confessed that they had deliberately crossed the border for fishing, KCNA claimed, adding the North however decided to repatriate them "from the humanitarian point of view".

The North took into account the fact that "all the crewmen honestly admitted their offence, repeatedly apologising and asking for leniency", the KCNA said.

The ship and crewmen would be handed over to the South at around 0930 GMT on Friday, it said. It is unclear how many crewmen were aboard the ship.

The South Korean government confirmed the report and welcomed the move by the North.

"We find it fortunate that our fishing ship and its crewmen are being returned," said a spokesman for Seoul's unification ministry handling North Korea affairs.

North Korean fishing boats have occasionally strayed across the sea border and have been repatriated by Seoul, but this is the first time a fishing boat from the South has done so since 2010, the spokesman said.

Through the 1960s and 1980s, the North is believed to have kidnapped dozens of South Korean fishermen and Japanese civilians to use them as tutors to train the North's spies to be sent abroad.

Tensions have spiked this year, with the North carrying out its sixth atomic test and launching missiles that appear to bring the US mainland within range, and its leader Kim Jong Un trading threats of war and personal insults with US President Donald Trump.