Moscow-traded shares in Gazprom Neft were down 1.2 percent as of 1340 GMT, wiping out a rise of 1.5 percent before the news.

A Gazprom Neft spokeswoman denied the reports of interruption, saying the refinery was producing and loading oil products after putting out the fire.

"The incident will not affect the off-loading of oil products on the Moscow market. The loadings are on schedule," she said on Friday.

But several traders said they were told by the refinery operator that it has halted off-loadings "until further notice."

"We don't know when the substation will return to normal.The plant stopped oil products off-loading at all its bases today (in the Moscow region)," a trader said.

A spokesman for the Emergency Ministry said the fire was extinguished at 1130 (0700 GMT)

Copyright Reuters, 2011