Star Alliance's TAP Portugal and Mozambique's flag-carrier LAM are to combine all direct flights operated by both airlines from Portugal to Mozambique and South Africa.
The agreement comes into effect from June this year.
TAP operates three flights per week between Lisbon and Johannesburg with a stop in Maputo, Mozambique, plus a fourth direct flight to the Mozambican capital.
"The decision by LAM to return to operating its own flights to Lisbon led to the redrafting of the commercial framework agreement between the two companies with a view to aligning the offer to the new reality," says TAP.
It says that, from the summer, four flights between Lisbon and Maputo - two from TAP and two from LAM - will operate as codeshare services.
LAM will also operate connections between Maputo and Johannesburg on its own aircraft in a schedule connecting with the Lisbon arrivals and departures. These flights will also carry the TAP code.
"In the near future the same operating model is being planned for Cape Town," adds TAP.