Two men wearing gas masks have robbed a grave at a Melbourne cemetery – stealing a particular item.

Victoria Police on Friday released images of the men they are seeking in relation to the theft.

“We believe this was a targeted incident,” Detective Inspector Graham Banks said.

The pair broke into the Preston General Cemetery shortly before 5am on July 30.

They climbed into a combined commercial mausoleum through a window before removing a casket belonging to a woman. Police say a diamond ring “of significant value” appears to have been removed from the body.

Inquiries with the dead woman’s family to see if anything else was taken continue. But there was no damage to any other crypts within the mausoleum.

“This is a highly unusual incident and I know there has been a lot of speculation, particularly in criminal circles, as to why this incident happened and who was responsible,” Banks said.

“While theft is not discounted as the only motive, police are receiving consistent intelligence that this was undertaken as a form of retribution against a relative of the deceased woman.”

Images of the pair were released in the hope they could be identified. They show the men wearing gas masks, hooded jumpers and dark clothing at the time of the incident.

One of the men had a larger build and the other was smaller.

“Police are keen to speak to anyone who has information about who is responsible and why, and this information as always can be provided anonymously,” Banks said.

Anyone with information is urged to call Crime Stoppers on 1800 333 000 or log onto crimestoppersvic.com.au.