Georgia's environment ministry ordered a two-week suspension of work on the section where the Baku-Tbilisi-Ceyhan (BTC) pipeline passes near the Borjomi valley -- a pristine alpine area that opponents say is under threat from the pipeline.
The stoppage comes as the BTC consortium, which is led by oil major BP, is racing to meet its deadline to complete the project and start pumping oil.
The 2.95-billion-dollar (2.42-billion-euro) pipeline will export up to one million dollars of crude a day from the landlocked Caspian Sea, through Azerbaijan and Georgia, to the Turkish Mediterranean port of Ceyhan.
"BP should have presented a document showing the maximum safety measures in place on the pipeline" in the Borjomi area, said Tamara Pirveli, a spokeswoman for Georgia's Environment Ministry.
"They did not present a complete document. As of yesterday (Thursday) the construction has been stopped for two weeks.
"In that time they will present the complete document -- and we are sure that they will do this -- and then they can start construction again," added the spokeswoman.
The stoppage affects a section of the pipeline 17.6 kilometres (10 miles) long, about 15 kilometres from the town of Borjomi.
That section has long been the focus of controversy. Borjomi is home to world-renowned mineral water springs. The water bottled from the springs is one of Georgia's biggest exports.
Some environmental groups say the pipeline is routed too near to the springs. In the event of an accident, landslide or terrorist attack, oil from the pipeline could leak into the aquifer which feeds the springs, they claim.
However BP insists that the section is safe. "We believe that the pipeline is secure with the world class measures incorporated into its design," said a BP spokeswoman in Azerbaijan's capital, Baku.
"This assessment is supported by the international financial institutions and commercial lenders involved in the project."
She added: "(Georgia's) President Mikhail Saakashvili has committed to the successful completion of the pipeline without any delays."
The spokeswoman said that despite the hold-up, the pipeline will still be finished on schedule.
"Although a decision of this type to stop work will inevitably impact the current construction schedule, we nevertheless expect that the pipeline will be completed on time to deliver first oil to Ceyhan in the second half of
Construction work was continuing as normal on all other sections of the pipeline in Georgia, Turkey and Azerbaijan, the BP spokeswoman said.
The BTC pipeline will dramatically boost oil exports from the Caspian Sea -- home to some of the world's biggest untapped oil and gas reserves.
The administration of US President George W. Bush is supporting the pipeline project. His officials want to see more Caspian oil on the world market, reducing the reliance for fuel on politically unstable regions like the Middle East.