SYDNEY, Australia — A man who stabbed and critically wounded another man in a park in a Sydney suburb on Saturday was inspired by Islamic State extremists, the police here said on Sunday.

Catherine Burn, a deputy police commissioner for the state of New South Wales, said at news conference that a 22-year-old Sydney man, whom police did not name, had been charged with committing an act of terrorism and attempted murder. He was expected to appear in court on Sunday morning.

Ms. Burn said the man was known to the police for other unrelated crimes.

“We will be alleging before court this was an act that was inspired by ISIS,” she said. “It was a deliberate act yesterday. It resulted in a person receiving extremely serious injuries.”

The unidentified 59-year-old victim was attacked while walking through a nature reserve in Minto, about 30 miles southwest of downtown Sydney. He was listed in serious condition at an area hospital.