Ubuntu 22.04 with Qt6 - qmake: could not find a Qt installation of ''

In Ubuntu 22.04 after installing Qt6 using

sudo apt install qt6-base-dev

calling qmake results in an error message:

qmake: could not find a Qt installation of ''

or

qmake: could not exec '/usr/lib/qt5/bin/qmake': No such file or directory

It is however possible to call/run qmake6. How to make qmake work and point it to qmake6?