Soldiers are reported to have taken over the headquarters of Zimbabwe's national broadcaster, ZBC, amid a growing political crisis.
Explosions have also been reported in the capital Harare but the cause is unclear, BBC reported on Wednesday.
Earlier, the country's ambassador in South Africa denied talk of a coup.
Zimbabwe's ruling party accused the country's army chief of "treasonable conduct" after he warned of a possible military intervention in politics.
General Constantino Chiwenga had challenged President Robert Mugabe after he sacked the vice-president.
Gen. Chiwenga said the army was prepared to act to end purges within Mr Mugabe's Zanu-PF party.
Tensions were raised further on Tuesday when armoured vehicles were seen taking up positions on roads outside Harare, although their purpose was unclear.
Some staff at ZBC were manhandled when soldiers took over their offices in Harare, informed sources said.
Workers were told that they "should not worry", a source added, and that soldiers were only there to protect the site.
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