HARARE, Zimbabwe — Zimbabwe’s military said early Wednesday that it had taken custody of President Robert Mugabe, the world’s oldest head of state and one of Africa’s longest-serving leaders, in what increasingly appeared to be a military takeover in the southern African nation.

After apparently seizing the state broadcaster, ZBC, two uniformed officers said in a short predawn announcement that “the situation in our country has moved to another level.” While denying that the military had seized power, they said that Mr. Mugabe and his family “are safe and sound, and their security is guaranteed.”

“We are only targeting criminals around him who are committing crimes that are causing social and economic suffering in the country in order to bring them to justice,” said the main speaker, who was identified as Maj. Gen. S. B. Moyo, the army’s chief of staff.

General Moyo — who was not widely known to the public but who was considered close to the commander of the Zimbabwe Defense Forces, Gen. Constantine Chiwenga — warned that “any provocation will be met with an appropriate response.”