China, Tanzania, and Zambia have signed a memorandum of understanding to rehabilitate a 1,860km rail line between Tanzania and Zambia, the Xinhua news agency reports.

The $1bn scheme was proposed by Beijing in February as a way of improving Zambia’s access to world markets – the line runs from the Tanzanian port capital of Dar es Salaam to the town of Kapiri Mposh in the country’s copper belt.

The agreement in principle was signed in Beijing and witnessed by Xi Jinping, along with Tanzanian president Samia Suluhu Hassan and Zambian president Hakainde Hichilema.

The single-track line was built between 1970 and 1975 and financed by an interest-free loan from the Chinese government. The project was presented at the time as a demonstration of solidarity between China and the newly decolonised African states.

The economic aim was to allow Zambia to export its copper and cobalt without going through colonial Rhodesia or apartheid South Africa.

More than 160 workers, including 64 Chinese nationals, died during construction after being stung by bees.

The line, still the longest in Africa, has since fallen into disrepair. It was announced in December that China Civil & Engineering and Construction – the company that built the original line – would examine the engineering and economic cases for revitalising it.

The Tanzanian and Zambian leaders were in the Chinese capital to attend the Forum on China-Africa Cooperation (FOCAC), a meeting held every three years to set a framework for relations between China and the countries of Africa.

Previous gatherings have covered industrialisation, agricultural innovations, security and possible projects to be carried out as part of China’s Belt and Road Initiative.