At least one person was killed and several injured in the explosion on Tuesday morning at Austria's Baumgarten distribution plant, a major hub for the transport of gas from Russia to countries all over Europe.
The facility has been placed offline and supplies to southern customers – including Italy – are "negatively impacted", its Austrian managers said.
"This morning, the gas flow from Russia was interrupted in Austria following a fire in the network run by operator Gas Connect," the Italian government said in a statement.
"The gas supply to Italian consumers will in any case be ensured by an increased gas supply from national subterranean reserves," the government said.
Authorities "are monitoring the situation with the operators to assess how long it will take for the supplies to start flowing again," it added.
Energy Minister Carlo Calenda said that the incident exposed "a serious supply problem".
Italy, which currently relies heavily on Russia for its natural gas, should diversify its supplies, he suggested.
"If we had had the [Trans Adriatic Pipeline], we would not have to declare a state of emergency," Calenda said, referring to a planned pipeline that would carry gas from Azerbaijan through Greece and Albania to Italy.
The Italian government has made the project a priority despite protests in Puglia, where the pipeline will be brought ashore. The route passes through a grove of ancient olive trees, hundreds of which have been removed.
Protesters have stalled construction by several months, but the government says it aims to have the pipeline supplying Italy by 2020.