UPDATE - 2.20pm:
The National Party President has stated that the party will contest the Northland by-election, following the resignation of MP Mike Sabin this morning.
Peter Goodfellow said details for candidate nominations would be confirmed in due course.
He acknowledged Sabin for his service to Northland constituents and the National Party since his election in 2011.
UPDATE - 12:15pm:
The Prime Minister has issued a statement following the resignation of Northland MP citing "personal reasons" for Mike Sabin's departure from Parliament.
The PM acknowledged Mr Sabin's resignation and said he was taking advice on the possible date for a by-election.
John Key also acknowledged Mr Sabin's service as an MP since he was elected in 2011.
12:10pm: Northland MP Mike Sabin has announced his resignation from Parliament, effective immediately.
Mr Sabin said he had decided to resign due to personal issues that were best dealt with outside Parliament.
A National Party statement said Mr Sabin would not be making any further comment on the matter.