Another Australian lawmaker says he may have to quit Parliament because of dual citizenship, days after a High Court ruling was thought to have finished the crisis.

The court disqualified five lawmakers on Friday because each was found to hold citizenship of Australia and another country and the constitution bans dual citizens from Parliament.

But on Tuesday, a senior senator from the governing Liberal Party, said he may have to quit parliament. Stephen Parry, who is president of Australia's upper house, says he has contacted UK authorities to check if he holds dual citizenship because of his British-born father.

Parry says the court's decision made it clear he will have to resign if his dual nationality is confirmed.