BEIJING, Aug. 7 -- The water level of an earthquake-formed barrier lake which is threatening residents of Yunnan Province with flooding is rising alarmingly, new monitoring results have showed.

The 15 km-long and 49 square-km lake near Longtoushan was formed when landlides caused by Sunday's deadly quake blocked the Niulan River.

As of Wednesday, the lake had already flooded about 370 homes. Given the strong possibility of the lake completely bursting its banks, many locals have fled, and 4,200 residents have been resettled from the lower reaches of the river.

Quake relief authorities said on Tuesday that the water level was rising at a speed of 0.16 meters per hour, projecting a rise of 3.84 meters per day.

However, the level rose by four to five meters in the 24 hours from 2 p.m. on Tuesday, the National Administration of Surveying, Mapping and Geoinformation has now said.

According to a statement released by the administration on Thursday, it assessed the rise based on hi-resolution images and videos of the lake shot from Monday to Wednesday by drones.

Earlier reports said a reservoir upstream is intercepting river water to reduce pressure on the lake, while two hydropower stations downstream are speeding up the discharge of water.

The army has said it plans to use about two tonnes of dynamite to blow up the blockage which formed the lake.

The 6.5-magnitude earthquake killed at least 589 people.