Dual-citizen Labor MPs formally resign

Three Labor MPs have formally quit parliament in the wake of Katy Gallagher's disqualification by the High Court over her dual citizenship.

Susan Lamb, Josh Wilson and Justine Keay were in similar positions to Ms Gallagher, and now face by-elections to be held as early as June 16.

Speaker Tony Smith also received the formal resignation of Tim Hammond, who quit as Labor member for Perth for family reasons.