China appears to have already implemented new U.N. sanctions on North Korea, with daily shipments of bilateral trade in their border area declining by as much as 30 percent, a diplomatic source with knowledge of North Korea-China relations said Wednesday.

China, North Korea's diplomatic and economic lifeline, backed new U.N. sanctions to punish the North for conducting its fourth nuclear test and launch of a long-range rocket this year.

The new U.N. sanctions, which require all countries to inspect cargo leaving and entering North Korea at all airports and sea ports, were adopted earlier this month.

"At this moment, the Chinese government is in internal discussions on specific plans to implement the new U.N. resolution," the source said on the condition of anonymity. 

"However, some measures of the resolution are being preemptively implemented for now," the source said. 

The source said daily shipments destined for and coming from North Korea at a border area between the two countries  declined by 20 to 30 percent since the new U.N. sanctions were approved. 

Chinese officials have said Beijing would "earnestly" implement the new U.N. sanctions, but the sanctions should not affect the well-being and humanitarian needs of North Korean people.

Winning China's cooperation is key to ensuring the effectiveness of U.N. sanctions against North Korea because China accounts for nearly 90 percent of the North's foreign trade.

Still, China is unlikely to put crippling sanctions on North Korea because a sudden collapse of the regime could spark a refugee crisis at its border and lead to a pro-U.S., democratic Korea on its doorstep, analysts say. (Yonhap)