Somalia's Islamist militant group al-Shabab has executed three men it accused of spying for the United States (US) Central Intelligence Agency (CIA) and other intelligence agencies, Ceoafrica reports.

The three were killed in front of a large crowd in south-western town of Yaq-Barawe.

Abdullahi Damey Mohamed Nur, 36, was found guilty of spying for the CIA, and earned a salary of $200 [£158] a month, as an al-Shabab judge said that Mohamed admitted helping the US target al-Shabab officials using drone strikes.

The judge also said that Mohamed Iman Hassan, 42, was executed for spying for Kenya and earned a salary of $150, and Mohamed Sharif Ali, 21, was accused of helping Jubbaland regional administration to collect information on al-Shabab.

The al-Qaeda-linked group arrests people who do not agree with its ideology and accuses them of spying and are later killed, which in 2011, Muslim cleric Ahmed Ali Hussein was chained and shot dead after being accused of being a CIA spy and belonging to a sect opposed to the group.

The group is fighting to overthrow the UN-backed Somalia government led by Hassan Sheikh Mohammed and form its own version of an Islamic state.