Uganda wants to link a new railway line it is building to one under construction in neighbouring Tanzania, a government document seen by Reuters showed, potentially opening up a new export route for minerals like gold, copper and iron-ore.

Uganda currently sends the bulk of its commodities exports via the Kenyan port of Mombasa and has already announced plans to link its Standard Gauge Railway project to one being built in Kenya, an initiative that remains in progress.

Uganda had not previously said it would seek to also connect the railway to Tanzania's network and its port of Dar es Salaam.

The Ugandan Ministry of Works and Transport document said the railway would run from the border with Tanzania through the south and southwest of Uganda, ending at the town of Mpondwe on the border with Democratic Republic of Congo.

"The main objective of the project is to connect the vast and mineral-rich regions of both countries (Uganda and Tanzania) to the port of Dar es Salaam ... while saving time and transportation costs," the document said.

The document also said that the African Development Bank (AfDB) could fund the project and that Democratic Republic of Congo could seek to link to it later.

A spokesman for the Ugandan ministry could not immediately be reached for comment.

The AfDB told Reuters it was considering a request to fund "preparation activities" for the rail project.

"The bank may consider financing the project, depending on the outcomes of the studies, if the project is found to be bankable," bank official Epifanio Carvalho de Melo said.