North Korea says it is waiting to confirm whether funds frozen in a Macau bank account have been released.
N Korea has pledged to shut down its main reactor
Pyongyang insists it will not start dismantling its nuclear programme, a condition of a recent international deal, until it has access to the money.
The dispute has delayed progress on the deal, and the first major deadline - for the North to shut its main reactor by Saturday - looks unlikely to be met.
Earlier this week, the US said the funding row had been resolved.
But the North has yet to withdraw any funds from the Macau bank in which the account is based.
US envoy Christopher Hill has arrived in Beijing for talks on the issue, in an effort to move the process forward.
Under the landmark agreement agreed in February, North Korea said it would "shut down and seal" its Yongbyon reactor within 60 days, in return for energy aid and other incentives from its dialogue partners - the US, China, Russia, South Korea and Japan.
Those 60 days end on Saturday, but so far the reactor has not been shut.
The deal has been delayed because of the financial dispute involving $25m (£12.7m) of North Korean funds, which was frozen in Macau-based Banco Delta Asia (BDA).
Mr Hill has been touring the region to move the deal forward
The North refused to make any progress toward disarmament until it was given access to the money.
The deadlock looked to have been resolved on Tuesday, when the US treasury department said the Macau authorities would lift the freeze, allowing North Korea to obtain the funds.
But there was no immediate response from Pyongyang, and no moves were taken to withdraw the money.
In its first public comments on the issue, the North's foreign ministry said on Friday it would "confirm soon" whether the funds had in fact been released.
"The DPRK [North Korea] remains unchanged in its will to implement the 13 February agreement, and will also move when the lifting of the sanction is proved to be a reality," the ministry said in a statement carried by official media.
Since the US claimed that the dispute had been resolved, North Korea has come under renewed pressure to start the process of shutting down its Yongbyon reactor.
"We know that the money is available," Mr Hill told the Associated Press on Thursday. "This is not a matter of Macau, it's a matter of whether [the North Koreans] want to fulfil what they said they would do for the denuclearisation process."
He told reporters it was "time for [the North Koreans] to get on with their obligations".
Eager to move forward with the deal, Mr Hill has recently visited Japan and South Korea to discuss the next steps, and he has arrived in China for further talks.
He said he was open to seeing North Korea's main nuclear negotiator Kim Kye Gwan during his Beijing visit, but he added that no meeting had so far been planned.
Despite the delays, delegates from all sides are still voicing optimism that the landmark agreement will work.
But the fact there have been so many problems in reaching the first of many steps in the process raises concerns about the long road ahead, correspondents say.