The move is being made so the country will honor its agreements with the companies and avoid the possibility of being taken to court, Prime Minister Boyko Borisov said.
"If we do not let companies start feasibility studies for the pipeline, we will be violating mutual agreements and the government may be held responsible to pay their losses," Borisov said.
The history of the South Stream project has been long and complicated. The project was designed to bring natural gas from Russia to Bulgaria and from there on to Austria.
Bulgaria wanted the South Stream Pipeline, which was supposed to be constructed by Russia. However, the European Union opposed its construction, saying it would breach the EU laws, and the Bulgarian government halted the project.
Russian President Vladimir Putin announced during his visit to Turkey on Dec. 1 that Russia had cancelled the South Stream Pipeline project, and a new pipeline would be built routing natural gas through Turkey instead of through Bulgaria.
Borisov said the Bulgarian government does not want to pay compensation to companies for the costs they have incurred. By allowing them to begin the start the studies, he said, the government will avoid giving companies a legal reason to take the government to the arbitration court.