An inmate killed in a Melbourne prison has been identified as young father Hassan Jeng.

The 23-year-old was fatally stabbed at Port Phillip Prison shortly before 7pm on Monday.

Paramedics worked on him at the prison but he died at the scene.

His partner Agnes Tontoe said she did not know how to break the news to the couple’s young children.

“They loved their daddy so much, his heart was so nice,” she told the Nine Network.

“I’m too young to be a widow.

“I don’t know why they have to end his life like this, I don’t know why they have to kill him like this.”

A number of inmates have been detained at the facility and the investigation is ongoing, Victoria Police said on Tuesday.

-AAP