Million of litres of highly acidic material spilled into waterways in February, leading to "mass fatalities" among fish, making water undrinkable and destroying crops, the farmers said in court papers as quoted by BBC.

This is one of the major environmental lawsuits filed in Zambia.

The farmers have claimed that the spillage has hit  300,000 households in the copper-mining region.

The lawsuit pits villagers, who are mostly subsistence farmers, against Sino Metals Leach Zambia and NFC Africa Mining, which are subsidiaries of Chinese state-owned firms, reported BBC.

A group of 176 farmers filed the papers in the High Court in Zambia, representing their community.

They alleged that the collapse of the dam was caused due to numerous factors that included engineering failures, construction flaws and operational mismanagement.

The firms did not comment on the lawsuit so far.

Last month, the US Embassy in Zambia had issued a 'health alert' where it raised concerns over widespread contamination of water and soil by toxic heavy metals stemming from the Sino Metals Leach Mine dam spill.

"The United States government has reassigned personnel from and imposed travel restrictions on U.S. government personnel in Chambishi town, all areas along the Chambishi Stream and Mwambashi River to the Mwambashi-Kafue confluence point, and Kitwe town," the US Embassy said in a statement.

"The U.S. government has further ordered U.S. personnel to avoid any travel to Kitwe Town that renders them dependent on drinking, or eating food cooked with, municipally available water," the statement said.