A Somali government minister says the two have been taken out of the capital and there's concern for their safety.

Separately, three foreign aid workers were also reported kidnapped on Friday night in a Kenyan town close to the Somali border.

The French agents "were caught assisting the apostate government and their spies", a senior Shebab officer said on condition of anonymity. He said they will "soon be tried and punished under the Sharia law, they will face the justice court for spying and entering Somalia to assist the enemy of Allah".

"The decision about their fate will depend on the outcome of the Islamic court that will hear the charges against them," he said.