SEOUL, March 22 (Reuters) - South Korean and U.S. forces will hold their largest-ever live-fire exercises in June in a show of force to North Korea, which has ratcheted up tension with numerous missile launches, South Korea's defence ministry said on Wednesday.

The exercises are part of a series of events marking the 70th anniversary of the alliance between the two countries this year.

"We've planned various anniversary programmes focusing on realising 'peace through strength' through action based on our strategic deterrence capabilities and the solid combined defence posture amid North Korea's evolving nuclear and missile threats," the ministry said in a statement.

"During the live-fire exercises, the combined forces will demonstrate the alliance's formidable firepower and mobility on an unprecedented scale."

South Korea plans to mark the 75th anniversary of the founding of its military in September with a display by the allies' forces of their "overwhelming deterrence and response capabilities" against the North, that will include South Korea's missile defence system, the ministry said.

In recent weeks, North Korea has been ramping up its military tests, firing an intercontinental ballistic missile last week and conducting a nuclear counterattack simulation against the U.S. and South Korea over the weekend.

The United States has about 28,500 troops in South Korea.

U.S. and South Korean forces have been carrying out various types of military training in recent weeks including air and sea drills involving American B-1B bombers, and their first large-scale amphibious landing exercises in five years.

North Korea has reacted furiously to those drills, calling them a rehearsal for its invasion.