Infrastructure Australia, the agency that advises the federal government, says it has not yet received a business case for Melbourne’s $125 billion Suburban Rail Loop project but that it does not need to provide a positive assessment for the Commonwealth to pump in more than $2 billion.

“We understand they’re working on a business case at the moment for submission to us at some stage,” Infrastructure Australia’s chief of project evaluation, David Tucker, told Senate estimates hearings in Canberra on Friday. He said the agency expected to receive it next year.