A breeding ground for a rare and little-known marsupial will triple in size after a funding boost from the federal and ACT governments.

Mulligans Flat Sanctuary, north-east of Canberra, will be extended to create more than 1200 hectares of predator-free woodland, federal environment minister Josh Frydenberg and ACT environment minister Mick Gentleman announced on World Environment Day.

Environment and Energy Minister Josh Frydenberg met Berry the Bettong at Mulligans Flat Wooland Sanctuary in Canberra on Monday. Credit:Andrew Meares

About $900,000 will be set aside in Tuesday's ACT budget to fund the expansion of the sanctuary.

The federal government will contribute about $600,000 to the project while the Woodlands and Wetland Trust will put up the remaining $300,000.