By James Reynolds
BBC News, Beijing
North Korean negotiator Kim Kye-gwan has warned that his country will not close its nuclear facilities until the US releases about $25m in frozen funds.
Kim Kye-gwan wants funds freed before making a deal
Funds at Banco Delta Asia in Macao were frozen over money laundering claims.
The comments were made as negotiators arrived in Beijing to prepare for a new round of nuclear talks.
Last month North Korea agreed to shut down its nuclear programme in exchange for aid and better relations with the outside world.
A month after they reached that deal, negotiators have come back to Beijing - and they are running straight into a possible problem.
The North Korean envoy Kim Kye-gwan has issued a warning - unless the United States releases frozen bank accounts, North Korea will not shut down its nuclear programme.
In other words - no money, no nuclear deal.
The money in question is about $25m held at Banco Delta Asia in Macao.
The funds were frozen in 2005 following US suspicions of money laundering.
The North Koreans are determined to get the money back and they may hope that other countries give way because of the importance of making sure the nuclear deal does not fall apart.
The chief US negotiator Christopher Hill says he does not think the frozen funds will be an obstacle.
"I think we'll work it out," he has told reporters in Beijing.