Police are appealing for help in their search for a Sydney man alleged to have stolen a large stash of drugs and firearms.

Jack Kemp, 38, from South Granville in Sydney's west, is wanted by police over the alleged theft of a large commercial quantity of pseudoephedrine and possession of firearms.

Pseudoephedrine is a common precursor drug used in manufacture of methamphetamine.

Kemp is described as being of Aboriginal or Torres Strait Islander appearance, between 180cm and 185cm tall with a solid build, dark hair and brown eyes.

Police say he is known by a number of aliases, including Jack Hay, Jacob Muirs and John Muirson.

They believe he has family in the Townsville and Rockhampton areas of Queensland and have urged them to come forward if they know his whereabouts.

Anyone with information about his whereabouts should contact Crime Stoppers on 1800 333 000.