Libya's oil output has been disrupted repeatedly in the chaotic decade since the 2011 NATO-backed uprising against its former leader Muammar Gaddafi.
NOC said in a statement that the Sharara closure has suspended crude oil supplies from the field to Zawiya terminal.
The Sharara field, one of Libya's largest, has been a frequent target for local and broader political protests.
The field is located in the Murzuq basin in southeast Libya. It is run by state oil firm NOC via the Acacus company, with Spain's Repsol, France's Total, Austria's OMV, and Norway's Equinor.
Negotiations are ongoing to resume production as soon as possible, NOC said.
The field was closed by protesters in Fezzan region in the south last week demanding public services and development projects.
"The loss of confidence in the continuity of supplying the global market with Libyan oil will result in Libyan oil remaining unmarketed," the oil and gas ministry said in a statement on Wednesday.
The ministry said that the closures of oil facilities "have serious consequences, and it may be difficult to quantify and explain all the damage it may cause."
"Closing and reopening the production requires maintenance operations and the treatment of technical problems, as well as a lot of effort, a long time, and a high cost to be borne by the Libyan state treasury", the ministry warned.
In July, production at the Sharara, Elfeel and 108 fields was stopped by tribal protesters over the abduction of a former finance minister.
(Reporting by Maha El Dahan and Reuters Libya newsroom;Editing by Elaine Hardcastle and Hugh Lawson)
