Tens of thousands of new housing lots are to be released by the Andrews government in Melbourne's growth corridors, as the sprawling city continues to expand.

The state opposition says the city is not sprawling fast enough, and has accused Labor of not keeping up with Melbourne's soaring population.

The release of the new housing lots will ultimately create 17 new suburbs across sites in outer Melbourne.

And, more than two years since it made a promise to trial a pilot to deliver cheap homes, the government has pledged to deliver 100 affordable houses – but only on government land.