N Korea reopens border business

North Korea practises a stop-go approach to border ties

North Korea has reopened its border to South Koreans working at the joint Kaesong industrial estate.

The opening came one day after the North had effectively closed the border in protest at a major US and South Korean military exercise.

On Monday Pyongyang also switched off military phone and fax lines, which are used to approve border crossings.

The hotline remains severed and the North requires hand-delivered notes to confirm which workers will cross.

"Cross-border trips by people and vehicles to and from the Kaesong industrial complex... have returned to normal," said Seoul's unification ministry spokesman Kim Ho-nyoun.

Kaesong appeal

Monday's border closure had stranded 80 South Koreans at Kaesong, a Seoul-funded joint industrial estate built just north of the border as a symbol of cooperation.

The agreement to reopen the border came after South Korean factory owners sent a written appeal not to hold the Kaesong complex hostage to any political situations.

About 39,000 North Koreans work in 98 South Korean firms at Kaesong, producing items such as watches, clothes, shoes and kitchenware.

The estate is a major source of foreign exchange for the impoverished North.

The hotline, which remains severed, is intended as a means of quick, direct communication at a time of high tension. It is also used to coordinate the passage of people and goods through the heavily fortified Demilitarized Zone.

North on alert

North Korea put its military on combat alert in response to the military exercise which it sees as a prelude to a US invasion.

The North had also warned Monday that any attempt to block what it calls an upcoming satellite launch would spark a war.

Seoul and Washington believe its real purpose is to test a long-range Taepodong-2 missile that could reach Alaska, in contravention of a UN resolution passed after the last missile test in 2006.

Last week, North Korea had warned it could no longer guarantee the safety of commercial flights through airspace it controls off the east coast.

Tensions have been high between North and South Korea since the South's conservative President Lee Myung-Bak scrapped his predecessors' policy of offering virtually unconditional aid to Pyongyang.

North and South Korea technically remain in a state of war since their 1950-53 conflict ended in a cease-fire, not a peace treaty.