At least 16 people have been killed, 11 are missing and more than 1600 have been displaced, as heavy rain across the Korean peninsula threatens to trigger fresh floods and landslides in South Korea.

Seven rescue workers are missing after their boats overturned in floodwaters, as parts of South Korea endure 44 consecutive days of rain, the longest monsoon since 2013.

Three rescue boats overturned and were swept downstream as they were trying to free a police boat stuck in wire by a dam near the city of Chuncheon, to the northeast of Seoul, Yonhap news agency reported on Thursday.

A children tram is submerged in Yeouido Hangang Park in Seoul. Photo: Getty

Witnesses said some occupants had disappeared but there was no immediate confirmation of casualties.

In Seoul, the Han River swelled over its banks after authorities were forced to open floodgates on upstream dams. Some highways by the river had to be closed, Yonhap reported.

On Wednesday, Prime Minister Chung Sye-kyun visited some of the hardest hit areas and urged the government to consider proposals to designate several provinces special disaster zones.

A decision on that could come by Friday, with the designation allowing areas to get more government aid.

The rescue effort is being complicated by coronavirus restrictions.

Emergency workers implemented measures to prevent the spread of the virus in gyms and community centres being used as shelters.

Heavy rain has also fallen in North Korea and state media published pictures of flooded streets but did not give any detail of damage or casualties.

The government in North Korea had issued a flooding alert for areas near some its biggest rivers and lakes, the Rodong Sinmun newspaper reported.

-with agencies