The United States is expected to respond to North Korea’s call for bilateral talks soon amid growing impatience in Pyongyang, which recently made announcements about progress in its nuclear arms program.

North Korea agreed to a US proposal last week to have two formal bilateral meetings before returning to a multilateral forum, according to a US magazine on global affairs, taking a step back from its previous position to return to the six-nation talks only if talks with Washington went well.

US magazine Foreign Policy reported that last week’s behind-the-scenes meetings between Sung Kim, the US State Department’s special envoy to six-party talks, and Ri Gun, North Korea’s deputy nuclear envoy, reaped "substantial progress", with the North agreeing to two of the three conditions presented by the United States.

Citing an official with access to information on the negotiations, FP said that the North also agreed to allow US special representative for North Korea policy Stephen Bosworth, who has been invited repeatedly to Pyongyang, to meet with its first vice foreign minister Kang Sok-ju.

"Bosworth’s visit would be seen as a failure unless some demonstrable progress was made and it is widely believed that only top officials in Kim Jong-il’s regime have real negotiating authority," the magazine said.