The United States on Thursday sought amnesty for an American citizen sentenced to 15 years of hard labour in North Korea for “hostile acts” against the regime.

US State Department spokesman Patrick Ventrell said Kenneth Bae’s trial for unspecified offences against the North lacked transparency and called for his “immediate release” amid concerns that the Korean-American tour operator could be used as a “bargaining chip” in negotiations between Pyongyang and Washington.

“What we’re urging the DPRK authorities to do is to grant him amnesty and to allow for his immediate release,” Ventrell said.

A US official, speaking on condition of anonymity, however, said Washington was not currently looking for an envoy to secure Bae’s release, who was arrested in November last year, reports Reuters.

The North is likely to use Bae, also known as Pae Jun-Ho, to get concessions from the US, while previous American prisoners were freed after visits of high-profile US leaders, according to AFP. But the official said the US is trying to break a cycle of having to resolve recurring crises with North Korea through transaction deals.

“Previous arrests of US citizens didn’t lead to changes in North Korean policy, resumption of bilateral dialogue or breakthroughs in US-North Korean relations,” Bruce Klingner, a former CIA North Korean analyst, said.