Police are alarmed by the discovery of a huge arsenal of weapons and ammunition in South Auckland last night.

About 45 high-powered rifles and shotguns were found at an Otahuhu property after police were called to a domestic incident about 9.30pm.

A 70-year-old man had allegedly made threats to use the weapons, police said.

Bags of live ammunition of compatible types and calibres were also found.

The firearms were seized and police were seeking to permanently confiscate the weapons.

A man was being questioned and would face a range of firearms charges.