(Adds PDVSA comments)
By Sailu Urribarri
PARAGUANA, Nov 4 (Reuters) - A blackout halted Venezuela's biggest oil refinery on Tuesday night, although officials said electricity supply had been re-established and operations were gradually starting up again.
"Works to restart (the refinery) have begun," Oil Minister Asdrubal Chavez said on social media website Twitter late on Tuesday.
It was not immediately clear what operations had resumed at the 645,000-barrel-per-day Amuay facility, or how long it might be before the entire complex was up and running.
The new oil minister, a cousin of late leader Hugo Chavez, added that the government was investigating what he described as a "strange" electrical failure.
The government of Nicolas Maduro often blames saboteurs out to harm the socialist administration for blackouts or refinery accidents. Critics say refinery issues are due to negligence and lack of investments.
An explosion at Amuay in 2012 killed more than 40 people, sparked a huge fire and halted operations.
On Tuesday night, electricity also went out in residential areas around the refinery. The shutdown led to heavy flaring that lit up the surroundings, one worker said.
State oil company PDVSA said in a statement there were no fires, explosions or accidents to report at Amuay.
The Cardon refinery, which is also part of the Paraguana Refining Center, is fully operational, and the incident will not affect PDVSA's ability to meet domestic and international demand, the company added.
PDVSA did not immediately respond to questions about the operational status of Amuay. (Reporting by Sailu Urribarri; Additional reporting by Alexandra Ulmer; Writing by Alexandra Ulmer; Editing by Clarence Fernandez)