South Korea on Thursday expressed hopes that its upcoming summit with China in Washington would offer "crucial momentum" to tackle North Korea's nuclear problem amid rising cross-border tensions stemming from Pyongyang's continued saber-rattling.

President Park Geun-hye and her Chinese counterpart Xi Jinping will hold their seventh summit on Thursday on the sidelines of the Nuclear Security Summit that seeks to jointly tackle nuclear terrorism.

"It will be the seventh summit, which is testimony to the fact that the bilateral relationship is closer than ever before," Seoul's Foreign Ministry spokesperson Cho June-hyuck said during a regular press briefing.

Topping the agenda for the summit is the implementation of the U.N. Security Council sanctions resolution, which was adopted early this month to punish Pyongyang for its nuclear test in January and long-range rocket test in February.

China has been regarded as the most crucial player in the enforcement of the sanctions given the sheer size of its trade and exchanges with the North. Two-way trade accounts for more than 90 percent of Pyongyang's aggregate trade.

Cho said that the focal point of the planned summit between Park and Japanese Prime Minister Shinzo Abe would also be the implementation of UNSC sanctions and their unilateral punitive measures. 

On the sidelines of the premier gathering on nuclear security, Park plans to have a series of summits, including a trilateral summit with Obama and Abe, to further pressure Pyongyang to renounce its nuclear ambitions and stop its provocative acts.

The North has been ratcheting up military tensions with threats of preemptive strikes against Seoul and Washington, claims of headway made in its nuclear and missile programs, and the launch of short- and mid-range ballistic missiles. (Yonhap)