Britain and the United States have warned their citizens in Tanzania to exercise caution ahead of possible anti-government protests on Thursday.
Police have promised a robust response to any demonstrations against President John Magufuli. A protest in February led to the death of a student hit by a stray bullet.
Britain and the US issued alerts on Tuesday warning of "possible" protests "across Tanzania" adding that police might use "tear gas and live ammunition".
They urged their citizens to avoid crowds and monitor local media.
The protest call has circulated on social media in recent weeks, although the likely response to it remains unclear.
Thursday coincides with the anniversary of the union of mainland Tanzania and the Zanzibar archipelago that together comprise the United Republic of Tanzania.