A late hiccup for Sydney's driverless metro train line has spurred another state to hold off on an exact opening date for its long-awaited rival.

Melbourne's $15 billion Metro Tunnel will open to the public in early December after early works to build the 9km twin tunnels and five underground CBD stations began in 2017.

The Victorian government has been tight-lipped on an opening date for months, only committing to it being later in 2025.

The opening of the $21 billion Sydney Metro was delayed by 15 days in 2024 after the rail safety regulator would not give approval before an earlier targeted opening date.

Victorian Premier Jacinta Allan said her government was reluctant to set a precise opening date as it was still awaiting final regulatory sign-off for its signature mega-rail projec

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