Police inspector injured in Sydney brawl

A police officer has allegedly been hit in the head with a stick as she tried to arrest a man during a massive street brawl involving up to 80 people in Sydney's west.

A large group of people were trying to get into a house party they weren't invited to on Lethbridge Street in Penrith on Sunday night, which led to a massive fight, police said.

A female police inspector used capsicum spray on three men who approached her and was allegedly hit with a stick on the side of her head while attempting to arrest a man for assault.

She had a minor head injury, but was able to continue working.

A 21-year-old man has been charged with affray. He was granted conditional bail and is due to face Penrith Local Court next month.