Meanwhile, Hong Kong media reported the apparent suicide of an official in the upstream city of Jilin, where a Nov. 13 chemical plant explosion caused the spill. Vice Mayor Wang Wei was found hanged, the Ta Kung Pao newspaper reported, citing anonymous sources.
Government and police officials in Jilin and provincial levels had no comment Thursday.
China's government has vowed to punish anyone found responsible for the explosion or spill. The head of the country's industrial safety agency warned this week that anyone who tried to hide evidence would be punished.
The spill dumped 100 tons of benzene and other chemicals into northeastern China's Songhua River, disrupting water supplies to millions of Chinese and straining relations with Moscow.
The government didn't announce that the Songhua had been poisoned until 10 days later on Nov. 23 — hours after the major city of Harbin was forced to shut down running water to 3.8 million people.
The Songhua flows into the Heilong River, which merges with the Wusuli River in the Russian border city of Khabarovsk to become the Amur.
The temporary dam would be built on a waterway linking the Heilong and Wusuli, which supplies water for homes and businesses in Khabarovsk, the official China Daily newspaper said.
The Wusuli is known in Russian as the Ussuri.
"China is going to do all it takes to reduce the possible impact of the pollution in Russia," Chinese Foreign Ministry spokesman Qin Gang said. "China agrees to give positive consideration to engineering projects or measures including setting up a dam."
Qin said the details for the dam project was still being worked out by both sides.
The spot was chosen because the water is only 3 feet deep and moves slowly at this time of year, the newspaper said. It said Chinese experts arrived Tuesday in the northeastern city of Jiamusi to study a Russian proposal for the dam.
China's plan adds to its increasingly ambitious efforts to contain human, economic and diplomatic damage from the incident.
China has apologized to Russia and promised this week to work closely with Moscow to minimize the spill's impact.
Also Thursday, Russian Vice Prime Minister Dmitry Medvedev met in Beijing with Chinese President Hu Jintao, who assured him that China "would take measures to effectively and responsibly minimize the pollution," state television said.
Hu also encouraged close contact between the two sides in moving forward, the report said.
Russian officials were trying to calculate when the chemicals would cross the border.
The nation's Emergency Situations Ministry anticipates pollutants in the Amur will worsen after Saturday, when the advance front of the spill was expected to hit, the ITAR-Tass news agency reported.
The head of the Far East branch of the Meteorological Agency, Alexander Gavrilov, said in Khabarovsk that the main chemical flow would enter the Amur no sooner than Dec. 19 and reach the city by Dec. 25. His comments were broadcast on Rossiya state TV.
Chinese engineers intended to build the dam in the next four days, ITAR-Tass said. Russian engineers were already working to increase the volume of water in the Amur's main channel to dilute the chemicals.
Meanwhile, Chinese authorities were investigating the death of Jilin Vice Mayor Wang, who had told reporters that the chemical plant explosion in the city of Jilin would cause no pollution.
"The exact reasons are unclear. The investigation has not reached a conclusion," a spokeswoman for the Jilin province government told Hong Kong Cable TV.
The country's chief industrial safety official warned that anyone who tried to hide the cause of the Nov. 13 chemical plant explosion that poisoned the Songhua River in the country's northeast will also be punished.
"Anyone, who were found guilty of dereliction of duty, will be harshly dealt with," said Li Yizhong, director of the State Administration of Work Safety, quoted by Xinhua.