A North Korean defector who swam across a sea border with South Korea while reportedly tied to floating plastic has been rescued and taken into custody, according to Seoul authorities.

Relations between the two Koreas were at an all time low in years under South Korea’s former President Yoon Suk Yeol, who was impeached over his martial law declaration last December, as the two sides engaged in tit-for-tat psychological warfare campaigns.

South Korean authorities began removing on Monday loudspeakers blaring anti-North Korea broadcasts along the country's border, Seoul's defence ministry said, as the new government of President Lee Jae Myung seeks to ease tensions with Pyongyang.