The tunnel near the town of Doupnitsa in southwestern Bulgaria would be shut down early on July 15 for emergency repair works, Bulgaria's Regional Development Minister Assen Gagaouzov said on July 14, as quoted by Dnevnik daily.

Construction crews will work for eight hours to reinforce the tunnel and fix the cracks that have been reported at the weekend. For the duration of repairs, traffic on the E79 European highway that passes through the tunnel would be diverted to Doupnitsa town centre.

Despite fears voiced by drivers, Gagaouzov was adamant that the situation was under control. "There is no danger for the tunnel to collapse; it just needs re-inforcing. We chose the best time possilbe [to carry out the works] - both for people travelling and those that will undoubtedly suffer from the redirection of traffic," Gagaouzov said, as quoted by Focus news agency.

E79 is the highway that links capital Sofia to Koulata on the border with Greece and is one of the busiest thoroughfares in the country. All traffic passes through it, given that the second tunnel, meant to carry traffic in one of the two directions, is still only 92 per cent complete, according to deputy regional development minister Savin Kovachev.

The completion of the second tunnel has been delayed by the need to re-inforce the terrain, but it could open for traffic as early as this autumn, Kovachev said.

The witness reports about cracks was the first time that serious problems were registered with the tunnel, Kyustendil regional governor Lyubomir Dermanski said, as quoted by Focus news agency.