The first stage of a new toll road in Sydney’s south – to be renamed the M6 motorway – will now be opened to motorists by the end of 2025, about a year later than planned.

The government has blamed the "revised timeline" for the twin 4-kilometre road tunnels from Arncliffe to President Avenue at Kogarah on the need to allow time for community and sporting facilities to be built or upgraded before construction begins.

The first stage of the motorway project renamed the M6 will now open to motorists towards the end of 2025. Credit:NSW government

It has also decided to rename the long planned F6 Extension as the M6 motorway to make it easier for motorists to easily comprehend Sydney's vast road network. The first stage of the M6 has been estimated to cost up to $2.6 billion.

Preliminary design work will begin next year once contracts are awarded, while tunnelling machines are expected to begin churning in 2022.