Sydney police officer suffers suspected broken nose in alleged assault

A senior constable has a suspected broken nose after being punched in the face in Sydney's west.

Police say officers were speaking to three males and a female at a South Penrith intersection at about 2.45am today when one of the males assaulted a 35-year-old leading senior constable.

The officer was taken to Nepean Hospital for treatment of a suspected broken nose.

His alleged assailant, an 18-year-old man, was taken into custody and is being questioned by police.