The note warns that hotels, embassies, restaurants and malls frequented by foreigners and tourists could be attacked with little or no warning.

It comes just hours after Kenyan authorities released the names of five men wanted for their links to the al-Shabab Islamist group.

They are on the most wanted list in Kenya for alleged attacks carried out in the coastal town of Lamu.

The jihadist group has been blamed for carrying out attacks in northern and coastal Kenya targeting civilians, security officers and government installations.

But the al-Qaeda affiliated group has suffered huge losses in recent days, losing top commanders, hundreds of fighters and huge swathes of territories in central and southern Somalia where they have been in control for decades.