Police arrest 21-year-old man over alleged sexual assault in Melbourne park

The man allegedly assaulted a woman at Mayer Park in Thornbury.

Police have arrested a 21-year-old man over the alleged sexual assault of a woman at knifepoint in a park in Melbourne's north on Saturday night.

Yesterday, police had appealed for the public's help in finding a man who allegedly produced a knife as he attacked a 32-year-old woman in Thornbury's Mayer Park.

In a statement today, Victoria Police said the 21-year-old man, who was of no fixed address, attended Preston Police Station about 11:00am.

The man remained in custody and was assisting police with inquiries, police said.

On Sunday, police said the woman, who was walking a dog, had entered Mayer Park about 10:30pm on Saturday night after she noticed a man ahead of her acting suspiciously.

Police said the man approached her and asked for help to find a lost possession before he pulled out a knife, pushed her to the ground and sexually assaulted her.

The woman managed to grab the knife in the struggle that followed and stabbed him, according to police.