Warplanes launched three air strikes on the Libyan city of Derna on Monday, a witness said, days after Egypt attacked camps there, saying it was targetting militants responsible for killing Egyptian Christians.
There was no immediate confirmation of Monday's strikes from officials in Libya or neighbouring Egypt, nor any claim of responsibility for the raid on the city at the eastern end of Libya's Mediterranean coast.
The witness said one attack hit the western entrance to Derna and the other two hit Dahr al-Hamar in the south.
Egyptian jets attacked Derna on Friday, just hours after masked militants boarded vehicles en route to a monastery in the southern Egyptian province of Minya and opened fire at close range, killing 29 and wounding 24.
Islamic State claimed responsibility for that attack in Egypt, the latest targetting Christian minority there - two church bombings also claimed by Islamic State killed more than 45 last month.
Egypt, which attacked Derna again on Saturday, has carried out a number of air strikes on its neighbour since Libya descended into factional fighting in the years following the 2011 civil war that ousted Muammar Gaddafi.
Islamist militant groups, including Islamic State, have gained ground in the chaos.
Egypt has been backing eastern commander Khalifa Haftar, whose Libyan National Army has been fighting Islamist militant groups and other fighters in Benghazi and Derna for more than two years.
Libyan National Army spokesman Col. Ahmad Messmari told reporters in Benghazi late on Sunday that Haftar's forces were coordinating with Egypt's military in air strikes and the weekend raids targeted ammunition stores and operations camps.
Egyptian President Abdel Fattah al-Sisi said on Friday the air raids targeted militants responsible for plotting the attack, and that Egypt would not hesitate to carry out additional strikes inside and outside the country.