North Korea reopens hotline with South

North Korea reopened a military hotline with the South today, a day after Washington and Seoul ended annual defence drills Pyongyang had called preparations for an invasion.

The North also confirmed it had detained two Americans on Tuesday for "illegally" crossing its border from China and said they were being investigated.

Washington said on yesterday that Secretary of State Hillary Clinton was trying to resolve the issue over the two female journalists, who were detained while filming a story for an online news company.

Pyongyang cut the military hotline, the only telephone link between the two Koreas, at the start of the annual US-South Korean drills on March 9. A spokesman for Seoul's unification ministry said it was restored earlier today.

But the move did not signal the North was ready to tone down its rhetoric ahead of a planned rocket launch early next month.

North Korean media called the drills the "biggest maneuvers for a nuclear war against the DPRK (North Korea) in history in terms of the aggressor forces involved and their duration".

Tension on the peninsula are already running with the North's announcement it would launch a satellite between April 4 and 8.

The North issued a notice to aviators saying it will close two routes in its airspace from April 4 to 8 between the hours 2am and 7am for a satellite launch, an official at Japan's transport ministry said.

Officials in Seoul and Washington say the launch is really a disguised test of its long-range Taepodong-2 missile.

The detention of the journalists comes at an awkward time for Washington, which has condemned the planned rocket launch.

"Two Americans were detained on March 17 while illegally intruding into the territory of the DPRK by crossing the DPRK-China border. A competent organ is now investigating the case," the North's official news agency KCNA said without giving more details.

South Korean media and diplomatic sources said this week North Korean security officials detained the two as they filmed across the Tumen River from the Chinese side of the border.

A media source has said the two women were working for Current TV, a US-based online news company.

A diplomatic source said earlier the reporters were on the frozen Tumen when taken by North Korean security guards. The Tumen runs along the eastern section of the border with China.

"What I can tell you is that we are working diplomatically to try to resolve this issue. Secretary Clinton is engaged on this matter right now," Robert Wood, a US State Department spokesman, told reporters yesterday.