Two US reporters detained for almost five months in North Korea have indicated that their arrest may have been a premeditated trap laid by Pyongyang at a time when the regime was looking for bargaining chips in a stand-off over its nuclear programme.

North Korean soldiers grabbed Laura Ling and Euna Lee, journalists for San Francisco-based Current TV, as they were making a documentary on the frozen River Tumen, which forms the border with China. They were detained from March until last month, when Bill Clinton, the former US president, secured their release on a trip to Pyongyang.

Mrs Ling and Mrs Lee said on Tuesday they were unsure whether their arrest was a trap but said their Korean-Chinese guide “behaved oddly”. They insisted they had no intention of leaving China, where they were documenting the activities of a North Korean human trafficking network, but the guide had urged them forward on to North Korean territory.