South Australian Premier Peter Malinauskas says expanding the state economy is his major priority as he promised not to succumb to hubris after a second resounding Labor byelection win in eight months.

The Australian Labor Party secured a swing of more than 13 per cent in the southern Adelaide suburbs seat of Black on Saturday. The Liberal Party has now been reduced to 13 seats in the 47-seat lower house and Mr Malinauskas’ standing as a national Labor star grows brighter.