Milk had been piped to the 69 stuck workers in the flooded shaft.
By 8:50am (01:50GMT) on Saturday, “the working places under the mine have all been inundated,” Xinhua said, citing rescue officials.
Wang Ziqi, director of the Shandong coal mine safety administration, said the trapped miners had only a “slim chance” of survival.
“The miners are all local men,” Wang Wei, a man who sells mining equipment in the region, said.
“Everybody here is very worried because we all know the mine and the miners … It hadn’t had problems before, none that I’d heard of anyway.”
More than 200mm of rain had fallen in Xintai, about 570km southeast of Beijing, since Thursday, causing a 50-metre breach of a levee of the Wen river.
Water poured into the 860-metre deep pit at the Huayuan mine, quickly overwhelming the mine’s pumps. It was not known at what level most of the miners were trapped, but 14 were 30 metres underground, according to Xinhua.
About 2,000 Chinese People’s Liberation Army troops, police and miners had closed a 40-metre section of the breached levee by Saturday evening, Xinhua said.
State television reported that Hu Jintao, the president, and Wen Jiabao, the premier, had urged local officials to spare no effort in attempting to reach the trapped miners as soon as possible.
Poor safety standards make Chinese coal mines the most dangerous in the world.
More than 4,700 workers died last year, according to official figures, but independent labour groups claim that up to 20,000 die annually, saying many accidents are covered up.
Chinese officials estimate that China suffers 1.49 mine deaths for every million tonnes of coal produced, compared with about 0.04 US deaths for every million tonnes produced in 2005.