A Mozambican Airlines airplane carrying 28 passengers and six crew members went missing en route from Mozambique to Angola, the airline said.
Flight TM470 took off from Maputo at 0926 GMT on Friday and had been due to land in the Angolan capital Luanda at 1310 GMT, but never arrived, the airline said in a statement.
"Initial information suggests it might have landed in Rundu, in northern Namibia near the border with Botswana and Angola.
"LAM airlines, aeronautical and airport authorities are trying to establish contact to confirm the information," it added.
Company spokesman Norberto Mucopa could not confirm the nationalities of the people on board the Brazilian-made Embraer 190 or if they included government officials.
"The last contact was in the north of Namibia," he told AFP.
LAM CEO Marlene Manave told journalists the last contact with the aircraft had been at 1130 GMT.
Heavy rain in the area where it disappeared complicated the search, she said, according to Canalmoz newspaper.
A police commander confirmed the incident to AFP in Namibia.
"We are busy searching. It's dark now and it makes our job a bit difficult," said Olavi Auanga, police commander of the Kavango West region, where the control tower lost signal with the aircraft.
An aviation officer in the area told AFP on condition of anonymity that unconfirmed reports suggested the airplane may have gone down in the Bwabwata National Park around 200 kilometres east of Rundu.
The 6,100-square-kilometre reserve covers the narrow strip of land formerly known as the Caprivi strip, a sparsely populated area with wetlands and dense forests.
The European Union banned LAM from flying in its airspace in 2011.
"Significant safety deficiencies" led to the blacklisting of all air carriers certified in Mozambique, the EU said at the time.
The concern was about Mozambique's civil aviation authority, rather than the track record of the various airlines.