UPDATE 1-All transit lines at Austrian gas hub back online - Gas Connect Austria

Austria@ (Adds detail, background)

VIENNA, Dec 13 (Reuters) - All main arteries that supply neighboring countries from Austria's main gas pipeline hub were back online before midnight after a deadly explosion there shut it down on Tuesday, the co-head of Gas Connect Austria said on ORF Radio on Wednesday.

The Baumgarten site in eastern Austria, near Slovakia, is a major regional transfer node, taking gas from as far away as Russia and pumping it towards neighbors including Germany, Hungary, Slovenia and Croatia and Italy, Baumgarten's biggest recipient.

"I can report that we were able to get back online all transit lines yesterday before midnight and that all of these lines are a 100 percent productive," Harald Stindl said.

Tuesday's explosion prompted Italy to declare a state of emergency as flows from the strategic site were cut off for most of the day.

Italian gas grid operator Snam said late on Tuesday that gas flows from Russia would resume by midnight and that Austrian authorities had authorized the resumption of gas transportation operations.

News of the blast sent gas prices in Europe soaring on fears it would restrict supply as winter sets in, as one third of Russian natural gas is transported via the transport hub, according to Gas Connect. (Reporting by Kirsti Knolle; Editing by Ludwig Burger and John Stonestreet)