Libyan police have found seven Egyptian Christians shot dead on a beach in eastern Libya, security officials and local residents have said.

A police officer told the Reuters news agency on Monday that the bodies were found with gunshots to the head outside Benghazi, where assassinations, kidnappings and car bombs are common and armed groups 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, said unknown gunmen had arrived at the Egyptians' Benghazi home and dragged them away the night before.

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

No group has 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 armed fighters in a country awash with weapons.

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

Source: Reuters