South Korea has caught a suspected North Korean man after he crossed the heavily fortified de-militarized zone (DMZ) between the two countries.

Troops tracked him for three hours on Tuesday as he made his way through the zone, which is filled with land mines and surrounded by barbed wire.

They are now investigating whether he tried to defect.

It is incredibly rare for people to defect via the DMZ but a similar incident occurred last November.

The man was located near a checkpoint at the eastern zone of the DMZ at 04:20 on Tuesday (19:20 GMT on Monday). It is not yet clear if he is a civilian or a member of the military.

"He is presumed to be a North Korean and we're conducting an investigation into details, including how he had come down and whether he wished to defect," the Joint Chief of Staffs said in a statement.

It added that it would be investigating the security breach.

A former gymnast defected via the DMZ last November by jumping over the border fence.

According to South Korean media, authorities had the young North Korean jump several times to verify his story of how he crossed the border.

An investigation found that a loosened screw in border sensors allowed the defector to cross undetected. South Korea's border sensor system is supposed to alert guards if there is some impact on the fence.

Following the investigation, South Korea's military announced it would check every sensor at the inter-Korean border.

Since taking power in 2011, North Korean leader Kim Jong-un is believed to have have ordered the tightening of border controls between the two sides and with China, including by laying more landmines.

But about 1,000 people defect from North Korea each year, fleeing a repressive state that has faced numerous accusations of human rights abuses.

Most North Koreans escape by crossing over the border to China from where they risk being sent back to the North.

Crossing via the DMZ is incredibly dangerous. If spotted and arrested by the North Korean military, those trying to cross would certainly be taken to a detention centre to be interrogated. They could be tried and sentenced to lengthy terms in labour camps.

The border and its fortifications have been in place since the Korean War ended in an armistice in 1953. North and South Korea remain technically at war as the fighting did not end with a peace treaty.