US Ambassador Nikki Haley told a Security Council meeting that Russia "cheated" on UN sanctions on North Korea, while Russia's UN ambassador said the US was blocking steps to foster cooperation between North and South Korea.
The United States on Monday accused Russia of "cheating" on UN sanctions against North Korea with plans for a railway project, oil transfers and ongoing business dealings with Pyongyang.
Russia shot back and charged that Washington was blocking steps to foster cooperation between North and South Korea and using a UN sanctions committee "as a select channel to punish" North Korea.
US Ambassador Nikki Haley told a Security Council meeting that the United States has evidence of "consistent and wide-ranging Russian violations" of the tough economic penalties imposed on North Korea.
Sanctions "cannot be an end in itself," Russian Ambassador Vassily Nebenzia responded. "You should, instead of creating roadblocks, promote the inter-Korean cooperation and dialogue," he told Haley.
The raucous meeting highlighted divisions between the United States, which is pushing for sanctions to be fully enforced on North Korea, and Russia, which argues that incentives must be offered to Pyongyang to move forward.
Led by the United States, the council last year adopted three sets of wide-ranging sanctions aimed at cutting off revenue to North Korea's ballistic missile and nuclear programs.
Haley said Russia had been "cheating" despite supporting UN sanctions resolutions.
"Step by step, sanction by sanction, and time and time again, Russia is working across the board to undermine the sanctions regime," she said.
The United States maintains that UN sanctions that have dealt a blow to North Korea's economy must remain in place until Pyongyang has completely scrapped its nuclear weapons and military programmes.
Row over UN report
Russia wants to develop railway links between North and South Korea to export coal from its Far East region and reach South Korean ports, Haley said.
Russia also blocked a US move to blacklist Russian ships allegedly involved in illegal ship-to-ship transfers of refined oil to North Korea and is refusing to expel a North Korean operative, Haley said.
In a rebuttal, Nebenzia said the plan for rail links was not in violation of sanctions resolutions and rejected accusations of a Russian ship involved in oil transfers.
He said Russia had asked for further information from the United States on the North Korean national.
The council meeting was called by the United States after a report by an independent UN panel of experts was amended under pressure from Russia to remove sections that deal with Russian businesses.
The United States blocked release of the report on implementation of sanctions in protest at the changes in the latest version.
China called for UN sanctions to be enforced but recalled that resolutions allow for a lifting of the punitive measures if there is progress toward denuclearisation.
Chinese Ambassador Mao Zhaoxu said "confrontation is a dead-end" and diplomacy must be "actively" promoted to bring an end to the standoff on the Korean peninsula.
China and Russia have argued that North Korea should be rewarded with the prospect of eased sanctions for opening up dialogue with the United States and halting missile tests.