Philip Ruddock wants to be a Sydney mayor

Former federal attorney-general and immigration minister Philip Ruddock is in the running to become a Sydney mayor.

Mr Ruddock, who retired from federal politics in 2016 as the second longest serving Australian parliamentarian, will run as the Liberal mayoral candidate in the northern Sydney council of Hornsby.

Mr Ruddock confirmed his candidacy in a statement on Twitter on Wednesday titled "I'm back".

"I never expected to return to elected office," Mr Ruddock said in the statement.

"That said I have always stated 'you enter and remain in politics to make a difference'."

Nominations for candidates wishing to contest the NSW Local Council elections closed at midday on Wednesday.