The Foreign & Commonwealth Office has warned British citizens in Zimbabwe to remain at home as political unrest sweeps the country.
Zimbabwe president Robert Mugabe is currently believed to be under house arrest in the capital Harare, with the military having taken control of the government.
However, the army has denied the move is a coup.
Seizing control of the national television station, military figures said they were targeting “criminals” around the government.
It is thought the power struggle centres on the bid to replace Mugabe, potentially with sacked deputy Emmerson Mnangagwa.
An FCO statement said: “Due to the uncertain political situation in Harare, including reports of unusual military activity, we recommend British nationals currently in Harare to remain safely at home or in their accommodation until the situation becomes clearer.
“You should avoid political activity, or activities which could be considered political, including political discussions in public places and criticism of the president.
“You should avoid all demonstrations and rallies.
“The authorities have sometimes used force to suppress demonstrations.”
The 93-year-old Mugabe has dominated the political scene in Zimbabwe since it gained independence from the UK in 1980.
Brits in Zimbabwe were also warned it is an offence to make derogatory or insulting comments about the president or to carry material considered to be offensive to his office.