The African Union (AU) says the al Qaeda-linked armed group, al Shabab, is planning attacks in Somalia using AU troop uniforms as disguises.

The African Union Mission in Somalia (AMISOM) said the uniforms were stolen by al Shabab fighters from military camps belonging to the 22,000-strong UN-mandated mission.

"AMISOM has information that due to panic [al Shabab] have plans to masquerade as AMISOM and dress in AMISOM troop's uniforms," AMISOM said in a statement on its Twitter account.

"These uniforms were accessed from AMISOM camps in the past and disguised as such, AS [al-Shabab] are organising to carry out atrocities. Planned atrocities are in areas generally controlled by FGS & AMISOM in order to turn the people against AMISOM by depicting it as the enemy," AMISOM said.

Al Shabab, which wants to impose strict Islamic law in the Muslim country of about ten million and is seeking to overthrow the country's internationally recognised government, have recently raided several army camps belonging to AMISOM.

A spokesman for the group, in a phone call, told Al Jazeera on Wednesday that it is true they have AU uniforms in their possession.

"It is not a secret that we took plenty of weapons, including armoured vehicles, ammunition and uniforms from them when we raided their camps and killed their soldiers," the spokesman said.

"We will continue attacking them and the apostate government because they are legitimate targets. We have never made that a secret. They [AMISOM] are planning to attack Muslim civilians and are looking for scapegoats for their future atrocities like they did in Marka before."

AU troops in July 2015 were accused of gunning down more than 20 civilians in the coastal town of Marka, claims that AMISOM strongly refuted.

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The Somali government said they were aware of the latest development.

"Terrorists will try everything in their power to harm innocent civilians. Our security services are on alert to stop those who want to harm our people," Abdisalam Aato, Somali government spokesman, told Al Jazeera by phone from the country's capital, Mogadishu.

"Terrorism has no place in Somalia. We request the public to work with our security agencies and report anything suspicious they may come across."

Last month, al Shabab raided and overran an army base belonging to Kenyan troops who are part of the AU mission in the small town of El Adde in southwestern Somalia, not far from the Kenyan border. The group then displayed boxes of ammunition and military vehicles they took from the camp.

In a similar dawn raid last June, on Burundian troops base in the town of Leego, about 100km northwest of the Somali capital, Mogadishu, al-Shabab overran the AU camp before making away with weapons and ammunition.

Then, in September, the group raided a Ugandan base in the farming town of Janaale in the Lower Shabelle region and made away with boxes of ammunition and an unknown number of uniforms belonging to the AU mission.

Follow Hamza Mohamed on Twitter: @Hamza_Africa