Asian diplomats have expressed doubts North Korea will meet a 14 April deadline to shut down a key nuclear plant, as agreed under a landmark deal.
North Korea agreed to shut down the Yongbyon reactor by 14 April
The timetable has been in doubt since a dispute between the North and the US over frozen North Korean funds disrupted six-nation nuclear talks.
China's nuclear negotiator Wu Dawei said the deadline was unlikely to be met because of the two side's dispute.
"There is a gap of a certain size," he said, according to Kyodo News.
South Korea's Foreign Minister Song Min-soon also said the money issue might not be sorted out in time.
N KOREA NUCLEAR DEAL
N Korea to 'shut down and seal' Yongbyon reactor, then disable all nuclear facilities
In return, will be given 1m tonnes of heavy fuel oil
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Under earlier 2005 deal, N Korea agreed to end nuclear programme and return to non-proliferation treaty
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"I basically do believe that the (bank) issue can be resolved by the timeframe," he said, according to South Korea's Yonhap news agency.
The dispute over some $25m (£13m) of funds held in a Macau bank has already led to March's round of six-nation talks ending without progress.
The US said on 14 March that it had completed an investigation into money-laundering allegations against the bank, allowing for the money to be transferred to a North Korean account in China.
But the transfer has still not taken place, amid reports Chinese banks do not want to receive the money in case it damages their credit ratings.
Under a landmark 13 February deal, the US, China, South Korea, Japan and Russia jointly agreed to supply energy aid and other incentives to North Korea if it "shut down and sealed" its main nuclear reactor at Yongbyon.
It was designed as the first step in a wider deal that would lead eventually to North Korea giving up its nuclear activities.