Gunmen have abducted five Egyptian diplomats and embassy employees in the Libyan capital, a spokesman for Libya's foreign ministry said.
The kidnapping appears to be retaliation for the detention of a Libyan militia leader in Egypt.
Egypt had earlier reported that its administrative attaché had been kidnapped in Tripoli late on Friday.
Libyan foreign ministry spokesman Mohammed al-Asswad said four other Egyptian diplomats were snatched in the early hours of Saturday. Those kidnapped included the cultural attaché, said al-Asswad.
The abduction came hours after Libya's state news agency reported the arrest of a militia commander, Shaaban Hadiya, in Egypt.
Mr Hadiya was a top member of the Revolutionaries Operation Room, a militia blamed for the abduction of Libyan prime minister Ali Zidan last year. It claims to answer to the Libyan military but is widely seen as operating independently.
Operation Room spokesman Adel al-Ghiryani called on Egypt to release Mr Hadiya, who was on a medical trip to Egypt.
Mr Al-Ghiryani told The Associated Press that he has no idea why Mr Hadiya was detained, and denied his group was involved in the kidnapping of the diplomats.
"We have no relation with this issue," he said.
Kidnappings are rife in Libya, suffering from a security vacuum since the 2011 overthrow of dictator Muammar Gaddafi.