North Korea has postponed next week's fourth round of reunions of families separated for half a century by strife on the Korean peninsula.

The reunions have been the most tangible symbol of reconciliation efforts between the communist North and market-oriented South.

The latest round of reunions were to have brought together a hundred people from South Korea and a like number from the North beginning next Tuesday. It would have been the fourth such meeting since last year's first-ever inter-Korean summit, which brought promises from both sides to work toward eventual reunification.

North Korea said it was postponing the visits because of what it called the "warlike" atmosphere in South Korea. South Korean forces have been on heightened alert since the September 11 terror attacks on the United States, its key ally.

Analysts in South Korea say the U.S. bombing campaign against terrorist targets in Afghanistan may have prompted Pyongyang to put off the reunions. Washington lists North Korea as one of the main nations sponsoring terrorism.

"Indirectly, they [North Korea] are probably expressing their unhappiness, dissatisfaction with America's aggressive action in Afghanistan," said Chun In-young, a professor of political science at Seoul National University.

Mr. Chun also says North Korea could also be using the postponement as an excuse to pressure Seoul to extend more economic aid to Pyongyang. "They need economic assistance from the South like grain, electricity and also they want investment for the Kumgang mountain tourist project. North Korea is calculating, recalculating their cost and benefit," he said.

This is the latest glitch to disrupt efforts to improve inter-Korea relations this year. North Korea has either halted or delayed a series of projects aimed at building confidence on the peninsula, much to the frustration of the South.

The previous three brief family reunions brought together hundreds of long-lost parents, children, or siblings separated in the chaos before and during the Korean War in the early 1950s. Tens of thousands of divided Korean families are on waiting lists, hoping to see loved-ones before they die.