The list includes firms from Russia, the U.S., South Africa and Australia.
Uganda's first oil licensing round is being watched by activists who hope the oil blocks will eventually go to firms with strong social and environmental track records.
The territory in the Albertine Graben region of western Uganda is ecologically sensitive and one of the blocks on offer lies in the Lake Edward basin inside Uganda's Queen Elizabeth National Park. Lake Edward extends into Congo, where it forms part of the Virunga National Park, a UNESCO world heritage site that is home to some of the world's last mountain gorillas.
Virunga has been the subject of a major international campaign to protect it from oil exploration. There is concern that drilling for oil on the Ugandan side of Lake Edward means there will be more pressure to open up the other parts of the lake for oil exploration.
"Given that all the blocks overlap with environmentally protected areas, the government must at a minimum publish information on the criteria for selecting companies — including what their environmental and social track record looks like," said George Boden of the watchdog group Global Witness. "It should also publish the true owners of these companies and the contracts they sign so that the public can see what kind of deals the government has negotiated and who will benefit from them."
The Uganda government needs to finalize regulations for the oil sector and establish a proposed petroleum authority before bidding can start, he said.
Uganda, which first discovered oil in the Albertine Graben area in 2006, hopes to begin crude production before 2020.