More than 10,000 US troops will participate in a large-scale landing drill in South Korea next week, the US military said Thursday, days after North Korea test-fired 25 projectiles in apparent protest at the continuing joint exercises.

The drill, code-named Ssang Yong ("Twin Dragons") and billed by local news media as one of the largest-ever of amphibious landing exercises by the two allies, will take place from March 27 through to April 7 on the southeast coast of South Korea.

It will involve 7,500 US Marines, 2,000 US Navy personnel, and an undisclosed number of Australian and South Korean forces, a US military spokesman told AFP.

Yonhap news agency said 3,500 Marines and 1,000 Navy sailors would take part from South Korea.

"Ssang Yong 14 is an annual combined exercise conducted by Marine and Navy Forces with the ROK (South Korea) in order to strengthen the interoperability and working relationships of the two militaries across the range of operations - from disaster relief, to complex expeditionary operations," US Forces in Korea said in a press statement.

The US Marines taking part in the drill belong to the 3rd Marine Expeditionary Brigade, based in Okinawa, Japan, it said.

A total of 12 South Korean and US Navy amphibious ships will also participate in the drill, Yonhap said.

South Korea, which hosts 28,500 American troops, and the US kicked off the annual Key Resolve and Foal Eagle exercises on February 24. They will run until mid-April.

In a show of force apparently intended to express anger at the continuing exercises, North Korea carried out a series of rocket and missile launches in recent weeks, sparking condemnation from Seoul and Washington.

The North has habitually slammed the exercises -- along with other military drills south of the border -- as rehearsals for an invasion.

Seoul and Washington say they are purely defensive.

Last week, the North's powerful National Defence Commission threatened to demonstrate its nuclear deterrent in the face of what it called US hostility.

But Seoul's defence ministry said there was no sign of an imminent nuclear test by the North, which staged three atomic tests in 2006, 2009 and last year.

China's special envoy Wu Dawei, who arrived in Pyongyang Monday, has been in talks with North Koreans to discuss ways to resume six-party talks on its nuclear programmes.

"Special Representative Wu Dawei ... held consultations with the DPRK (North Korea). Major topics include the situation of the Korean Peninsula and how to resume the Six-Party Talks," Chinese Foreign Ministry Spokesman Hong Lei told journalists on Wednesday.

Six-party talks involving the two Koreas, China, the US, Russia and Japan have been stalled since December 2008.

The North and China want to resume the negotiations, but Washington and South Korea say before a resumption of discussions, the North must first show it is serious about the process, notably by shutting down a uranium enrichment programme which the West believes could be aimed at building a nuclear bomb.