Two people have died in a Sydney hospital after eating death cap mushrooms.

A third person is still being treated at Royal Prince Alfred Hospital, a spokeswoman says.

Four people became ill after eating the poisonous mushrooms at a New Year’s Eve party in Canberra but one was discharged from hospital on Tuesday.

A 52-year-old woman and a 38-year-old man were among those being treated at RPA.

It is believed the four people had may have mistaken the poisonous mushrooms for mushrooms used in Chinese cooking.

The mushrooms are usually found in Canberra in autumn, near oak trees, but recent summer rain has spurred the growth of the mushrooms.