SEOUL/KATHMANDU -- Heavy snowfall is delaying Nepalese rescue workers' efforts to save four South Korean school teachers who went missing while trekking a circuit route of Annapurna in the Himalayas, officials here said Sunday.

The four South Koreans who went missing in an avalanche during a Annapurna Base Camp trek Friday morning remained unaccounted for as of Sunday even as South Korean and Nepalese authorities try to expand their search efforts. 

Nepalese rescue workers have rampped up their ground and air searches, but heavy snowfall and the resulting five-meter-deep snow accumulated on the scene were posing major challenges to their search efforts, officials here said.

On Sunday, the Nepalese government is set to mobilize a team of up to 10 more experienced police officers for the search efforts, resuming the rescue efforts that were put on hold early Saturday afternoon due to the dire weather conditions.

South Korea also dispatched an emergency response team of two government workers along with officials from an education body and a tourism agency to Kathmandu, the capital of Nepal, to assist the search operations, while the South Korean consul based in the Nepalese capital departed for the accident scene to call for the continuation of the rescue operation.

The South Korean officials said two more government workers will leave for Nepal later in the day to join the emergency response team at the scene.

"(The Ministry of Foreign Affairs) will continue to provide consular assistance for the swift rescue of (the trekkers) in coordination with the Nepalese government and other related bodies," according to the officials.

The four missing teachers -- two women in their 30s and 50s and two men in their 50s -- were trekking the Deurali part of the Annapurna Base Camp trek Friday morning as part of a team of nine trekkers when an avalanche engulfed them. Two Nepalese guides also went missing.

The five others, trailing behind the affected teachers, took shelter at a nearby lodge before being airlifted to a safe place by helicopters later.

The teachers were part of a 39-member volunteer team dispatched in three groups to Nepal by the education office of South Chungcheong Province.

President Moon Jae-in vowed the upmost efforts to find the missing trekkers in a Facebook message posted on Sunday.

"The government will do its best for the search and rescue (of the teachers) to the end in cooperation with the Nepalese government," Moon said. (Yonhap)