The North Korean deposits have been frozen in Banco Delta since Washington blacklisted the small, privately run Macau-based bank 19 months ago on suspicion that the funds were connected to money-laundering or counterfeiting.
Washington had promised to resolve the issue by mid-March as part of an agreement last month on North Korea's nuclear disarmament.
On Saturday, North Korea's nuclear envoy said that Pyongyang would not shut down its main nuclear reactor until the funds were released.
The long-running six-party talks reached a breakthrough accord on February 13, giving North Korea 60 days to shut the Yongbyon reactor and allow in international inspectors in return for aid and security pledges.
Negotiators from the two countries, along with South Korea, Japan, Russia and host China are expected to resume discussions on Monday at Beijing's Diaoyutai State Guesthouse to hammer out details to February's agreement.
Diplomats said talks to shut the North's Yongbyon nuclear reactor were going smoothly after working group meetings over the weekend.
The chief US envoy to six-party talks said on Sunday that North Korea was on track to fulfil its side of the disarmament deal by shutting down its main atomic facility next month.
Christopher Hill said: "I think we are on schedule for the shutdown of the facilities and monitoring by the IAEA."