Associations that have been leading massive protests against former South Korean President Park Geun-hye, who was recently impeached and detained, announced Monday a campaign to halt the deployment of the controversial THAAD anti-missile system.

The organizations - including two Buddhist and two Christian groups and the National Conference of People in Sovereignty, one of the most active organizations in the anti-Park protests - said in a joint statement they will send a delegation to the United States in the next few days to coincide with a summit in Florida between US President Donald Trump and his Chinese counterpart, Xi Jinping.

China, along with Russia, opposes the deployment of the US-built THAAD, or Terminal High Altitude Area Defense, system over fears that it will compromise their own defense systems.

China has also implemented an economic boycott against South Korean companies and interests over the deployment.

The delegates will hold demonstrations outside the White House and will send a protest letter to Trump and the United Nations, saying the decision adopted by the Park administration "should stop being valid immediately upon her impeachment", according to the statement.

They are also considering staging protests outside the US embassy in Seoul from May 9 onwards.

In July, Seoul and Washington approved the deployment of the THAAD, designed to intercept missiles launched by North Korea, in central South Korea.

In South Korea, the decision was strongly criticized by several opposition parties, pacifist organizations and left-wing parties, who said the measure will worsen the already fragile ties between South and North Korea, which have been technically at war for 70 years now.

Following her impeachment on Mar. 10 for corruption and abuse of power, Park has been in preventive detention since March 31.

South Korea is expected to hold elections for a new president on May 9.

Liberal candidate Moon Jae-in, who is tipped to win, has not completely rejected the THAAD system but has said it was a hasty decision and should be reviewed.