The Coalition has blamed a rogue email from a minister's office for its "regrettable" decision to back One Nation leader Pauline Hanson's incendiary motion that declared, "It's OK to be white."

Senator Hanson's motion condemning so-called "anti-white racism" was defeated in the Senate on Monday, but was backed by 23 Coalition senators and strongly endorsed on Twitter afterwards by cabinet ministers.

The phrase "it's OK to be white" is widely associated with alt-right, white supremacist and neo-Nazi movements, particularly in the US.

One Nation leader Pauline Hanson put forward a motion declaring: "It's OK to be white." Credit:Alex Ellinghausen

Amid the fallout on Tuesday morning, Prime Minister Scott Morrison said the actions of his own senators were "regrettable", and asked the government's leader in the Senate, Mathias Cormann, to explain.