A teenage girl injured in a crash near Balclutha earlier this month has died in hospital.

The 17-year-old was critically injured in a two-vehicle crash on State Highway 1 south of Balclutha on December 6.

In a statement, police said she had died in Dunedin Hospital on Boxing Day.

Investigations into the crash are ongoing.

After the crash, police said they wanted to hear from any witnesses, or anyone who had seen the vehicles involved - a light green-coloured Land Rover Discovery travelling north and a silver-coloured Toyota Blade heading south - before the accident occurred.

The girl's death brings to three the number of people who lost their lives on southern roads that weekend.