Libyan police have found seven Egyptian Christians shot dead on a beach in eastern Libya, security officials and local residents said, in the second such execution-style killing since the start of the year.

A police officer told Reuters the bodies were found with gunshots to the head outside Benghazi in the east, where assassinations, kidnappings and car bombs are common and Islamist militants are active.

"They were killed by headshots in execution style," a police officer said. "We don't know who killed them."

A local resident and an Egyptian worker, who asked not to be identified because of fears for their security, said unknown gunmen had arrived at the Egyptians' Benghazi home and dragged them away the night before.

Security sources confirmed the Egyptians were Christians. No further details were immediately available about how they were killed or whether they were shot on the beach.

No group claimed responsibility. Three years after the revolution that ousted Muammar Gaddafi, Libya's weak government and army struggles to control brigades of former rebels and Islamist militias in a country awash with weapons.

Last month, a British man and a New Zealand woman were shot execution-style on another beach 100 km (60 miles) to the west of the capital Tripoli.