Hungary hopes to finish building an emergency dam by the end of Tuesday, to hold back a reservoir of toxic sludge.
The Prime Minister's spokesman Peter Szijjarto told private broadcaster TV2: "We have 4,000 people and 300 machines working at the scene, so we are doing our utmost to prevent another tragedy."
About one million cubic metres of red mud leaked out of an alumina plant reservoir into villages and waterways last week.
Seven people died and more than 120 people have been injured.
Kolontar was evacuated on Saturday after cracks appeared in the northern wall of the reservoir, threatening a second spill of the toxic red sludge.
Disaster crews spokesman Tibor Dobson said residents must remain in emergency accommodation even though no further disturbance in the cracked reservoir wall had been found.
A team of EU environment experts was due to arrive in Hungary on Monday to provide authorities with help in dealing with the disaster.
The nearby town of Devecser, home to 5,400 people, remains on alert. The military has sent more than 300 soldiers and 127 transport vehicles into the town and five trains have been put on standby in case it has to be evacuated.
Hungarian Prime Minister Viktor Orban is due to inform lawmakers of the government's plans in parliament later on Monday. He is also set to make a national address.