A bomb exploded under the car of an Egyptian diplomat in Libya's second city Benghazi on Monday without causing any injuries, a security source in the city told AFP.
"Unidentified people in a vehicle that passed in front of the home of the first secretary at the Egyptian consulate threw a home-made device at his car which was parked outside," the security official said on condition of anonymity.
"The car exploded but no one was hurt," he said.
Abdelhamid al-Rafii, the diplomat, declined to comment about the incident.
The blast came after calls on social networking site Facebook for anti-Cairo protests over the allocation of frequencies on Egypt's Nilesat to officials from the toppled regime of Moamer Kadhafi who now live there.
Benghazi was the cradle of the revolt that toppled the long-time dictator last year.
Monday's incident also came after authorities in the capital Tripoli said they had arrested the key suspect behind two deadly car blasts on Sunday and three of his accomplices, identifying them as Kadhafi loyalists.
"The key suspect was arrested and admitted that he was directly responsible (for Sunday's attacks in Tripoli) along with four other people," Deputy Interior Minister Omar al-Kadhrawi told a news conference.
Police are still hunting for a fifth suspect, he said.
Other former regime officials, who fled to neighbouring countries such as Tunisia and Egypt, are also implicated in Sunday's attacks, Kadhrawi said.