Police are searching for a man who allegedly burst into an Islamic school in western Sydney and threatened staff and students with a machete.

CCTV images released on Friday show an obese man of Pacific Islander appearance, believed to be about 20 to 25 years old, carrying a knife the length of his forearm.

A CCTV image of a man who allegedly carried a machete into an Islamic school. Credit:NSW Police

Police have been told that he entered al-Faisal College in Minto about 2.10pm on Thursday armed with the knife.

"The man spoke with a female staff member at the location, left a short time later and was last seen in Kitson Road," a police spokesman said.