Libya's embassy in Egypt was closed indefinitely from Sunday, the mission said on its Facebook page citing security concerns.
"The embassy of Libya in Cairo... suspended its work due to security reasons starting Sunday and until further notice," a statement said without giving further details.
It however flatly denied in a separate statement reports suggesting that some embassy staff had broken ranks with the UN-recognized Government of National Accord based in Tripoli.
The GNA's foreign ministry confirmed that the embassy had been closed indefinitely, in a statement on Facebook.
It said the work at the mission was suspended in order to protect staff after a series of recent "violations" targeting the embassy, including attempts by some to "blackmail" employees in order to obtain money.
The foreign ministry gave no further details but said "work is underway with the Egyptian authorities to put an end to these violations and secure the embassy as required".
The embassy would resume its operations when it is secured, it added.
The Libyan embassy in neighboring Egypt has long been at the center of a power struggle between the country's rival administrations in the east and the west.
Libya has been mired in chaos since a NATO-backed uprising that toppled and killed the Libyan dictator Muammar Gaddafi in 2011.
The UN-recognized government is contested by a parallel administration in the east, backed by military strongman Khalifa Haftar, who in April launched an assault to seize Tripoli.
On Thursday, Haftar announced a "decisive battle" to wrest the capital from the GNA.
GNA Interior Minister, Fathi Bashagha, responded saying his government was ready "to push back any mad attempt by the Haftar putsch leader".