(Adds details, background)
TRIPOLI, Nov 2 (Reuters) - Libya's National Oil Corporation (NOC) said on Thursday production at the northeastern Sara oilfield had dropped by 50,000 bpd due to protests.
It also linked the protests to a contract dispute with Wintershall, saying the German firm had decided to shut production "without consulting NOC".
On Wednesday, protesters in Jakhira said they had blockaded production, accusing the NOC of failing to respond to local demands.
Wintershall confirmed earlier on Thursday that protesters had demanded a shut down of some of the production from oilfields in its concession areas.
The NOC has been in a contract dispute with Wintershall since early this year. They struck an interim deal to resume production in June.
The NOC said in its statement that it was "very concerned" at what it said was Wintershall's action in cutting production.
"We have demanded an explanation, particularly since the protests at Jakhira are explicitly intended to block the implementation of new contract terms for Wintershall," the statement said.
"We will not allow Wintershall to go back on its contractual commitments to the people of Libya."
Wintershall, BASF's oil and gas subsidiary, said earlier it was in "close contact with the community and NOC" and could not comment further at that time.
Editing by Alison Williams