Somalia's Al-Shabaab militant group has executed seven civilians who it accused of "spying" in three different parts of the fractious country, a government official has said.

"In Bardera city in the southern Gedo region, they [Al-Shabaab] killed four people. In the neighboring Hiran region, two other people were killed, along with one person in the [southern] Gambole area," Ibrahim Adan, district commissioner for the Gedo region, told The Anadolu Agency.

According to the official, all seven were killed in public by firing squad within a period of 24 hours.

On its Andalus radio channel, the militant group alleged that one of those killed in Bardera had worked for the CIA, the U.S. intelligence agency, and had played a vital role in the recent death of Al-Shabaab spy chief Absidhakur Tahliil, who was killed in a U.S. drone strike last week.

Two others were accused of providing intelligence to Ethiopia, while another was charged with helping the U.S. gather information on Al-Shabaab leaders when the group still controlled the port city of Barawe.

The two killed in Hiran were accused of collecting information for Djiboutian and Somali militaries, according to the broadcaster.

Al-Shabaab has recently suffered several major blows, losing most of its strongholds in the southern and central parts of the country to Somali and African Union troops. Several group leaders have also been killed in recent U.S. drone attacks.

U.S. drone attacks are said to rely heavily on accurate intelligence gathering on the ground.