Joanna Cherry said Holyrood should pass legislation for a consultative referendum.
Some MPs cheered as royal assent was confirmed for the European Union (Withdrawal Agreement) Act.
A new vote will be opened this week by the Educational Institute of Scotland (EIS).
It will recommend Holyrood does not consent to the UK Government's Withdrawal Agreement Bill.
As Boris Johnson's government lays out its legislative agenda, it dismisses a 2020 indyref as a 'damaging distraction'.
Labour councillor Alison Evison will speak at the Local Government Association conference.