Train services between Tanzania and Zambia have been paralysed by a strike by more than 1,500 Tanzanian workers.
A union official said workers had not been paid for five months by Tanzania's government because of a financial crisis at the railway authority.
The government has not yet commented on the strike.
China funded the building of the track, which stretches for 1,860km (1,155 miles), in the 1970s to boost links between the neighbours.
It gave the two governments a $500m (£330m) interest-free loan for the project.
However, the Tanzania-Zambia Railway Authority (Tazara), set up by the two governments to operate the service, is running at a loss, says the BBC's Tulanana Bohela in Tanzania's main city, Dar es Salaam.
The authority is desperately seeking a private investor to prevent its collapse, as the Tanzanian and Zambian governments are reluctant to continue financing it, she adds.
People in rural areas normally use the rail service. It is also used to transport cargo, especially copper and timber, from Zambia to Tanzania, our reporter says.
Tanzania Railway Workers Union official Erastus Kihwele told BBC Focus on Africa that the two government should seek "emergency funds" to pay employees.
He said many of them had no money to pay rent or the school fees for their children because they had not been given their salaries for five months.
The strike had been called for a week, but could continue if their demands were not met, Mr Kihwele added.