Former President Bakili Muluzi of Malawi was placed under house arrest amid a government investigation into an alleged coup plot.
The arrest set off clashes between police and supporters who had gathered in the capital, Lilongwe, to greet Muluzi on his return from Britain.
Ernest Malenga, a senior government official, said Muluzi was flown directly from the airport to the city of Blantyre, where he has a home.
"Police officers are currently interrogating him" and have searched the home, Malenga said.
It was not immediately clear what charges Muluzi faced, his lawyer said.