Australian will hold an unprecedented five by-elections on the same day in July due to a political crisis over a 117-year-old constitutional ban on dual citizens holding seats in Parliament.

Speaker Tony Smith told the House of Representatives on Thursday that the by-elections in four states will be held July 28.

The elections give Prime Minister Malcolm Turnbull a chance to increase his conservative coalition's single-seat majority in the House, where parties need a majority to govern. Four of the electorates had been held by dual citizens belonging to the center-left opposition Labor Party and one was held by an independent legislator.

But a firmer grip on power could be short-lived, with Australia facing a general election within a year and potentially as early as August.