SEOUL (AFP) - South Korea said Wednesday it had dismantled a Christmas tree-shaped tower near the border with North Korea which had previously been used for a seasonal lights show that drew angry protests from the atheist regime in Pyongyang.

North Korea has repeatedly demanded the destruction of the 20m-high steel tower on top of a military-controlled hill just 3km from the heavily fortified border.

In the past, it has even threatened to shell the tower that the South has allowed civilian groups to decorate with lights - including a giant illuminated cross at the top - over the Christmas season.

The Defence Ministry said it was dismantled for the sole reason that the 43-year-old structure had become unsafe. "The decision was unrelated to inter-Korean relations. Safety was the main reason," a ministry spokesman told AFP, adding that work to remove the tower had begun back in August. "There is no plan to replace it with a new one," he said.

The South switched off the tree under a 2004 deal to halt official-level cross-border propaganda. It also suspended loudspeaker broadcasts and a propaganda leaflet campaign using large helium balloons.

The deal was scrapped in 2010 following the sinking of a South Korean warship which Seoul blamed on a North Korean submarine.

In 2011 the tower was not illuminated in the wake of North Korean leader Kim Jong Il's death and it stayed dark over Christmas 2013 when military tensions were running high.

The North has always condemned the Christmas lights show as a provocative display of psychological warfare.

The dismantling of the tower comes after an agreement reached during a surprise visit to the South by a top-ranking North Korean delegation earlier this month to resume high-level talks suspended since February.

The remaining irritant for the North is the continued launching of anti-North leaflets over the border by South Korean activists.