Labor is planning a dramatic counter-attack against Coalition MPs if the Turnbull government "goes nuclear" and starts unilaterally referring opposition MPs to the High Court over citizenship doubts.

Fairfax Media understands the ALP has a hit list of eight Coalition MPs - in the Senate and the House of Representatives - that it believes still have unanswered questions about possible dual citizenship.

Following the shock revelations about Deputy Prime Minister Barnaby Joyce, the government has been contemplating using its numbers to refer at least four Labor MPs - Justine Keay, Susan Lamb, Maria Vamvakinou and Tony Zappia - to the court to have their eligibility tested.

Such a move would set a dangerous precedent of partisan referrals, setting the stage for a damaging free-for-all.