Former South Australian Liberal leader and now Labor Government Minister, Martin Hamilton-Smith, says the Liberals cost themselves the state election in March.

The now-independent Liberal has blasted his former colleagues in an address to the SA Press Club.

Mr Hamilton-Smith says he knew the Liberals were going to lose the election.

The former opposition leader says the Liberals’ small target strategy and big election spending in safe seats rather than key marginals ultimately cost them victory.

Mr Hamilton-Smith also says the Liberals should have campaigned harder to save carmaker Holden, which is closing down its production in northern Adelaide by 2017.

Ahead of giving his speech, Mr Hamilton-Smith commented to reporters he was not fussed by the boycotting of the Press Club event by state Liberal Party MPs.