There are new concerns that youth gangs are attempting to ambush Victoria Police officers by luring them to backstreets with no possible exits, an internal memo reveals.

Following a string of violent attacks in Melbourne’s western suburbs, an internal memo was circulated to members of Victoria's police force outlining "30-40 African" gang members' failed plans to lure officers into a laneway, The Herald Sun reports.

“Police saw a group of Africans who were being very hostile... as the vehicle approached Destiny Lane, a group of 30-40 Africans ran towards Destiny Lane,’’ the memo reads.

“It’s believed this was a deliberate ploy to lure police into the laneway, with no escape or exit paths unless they drove through [a] group of people … [where they could be] easily surrounded.’’

The memo comes amid fears two gangs mostly made up of African youths may have formed an alliance.

View photos Police were forced to retreat when partygoers began throwing rocks at them. Source: 7 News More

View photos Heavily armed riot police had to be called in to break up a Werribee party after the first officers to arrive at the Airbnb house were pelted with rocks. Source: 7 News More

In the early hours of Wednesday morning, police were called to a Werribee address in the city's west where they faced an onslaught of flying rocks and were forced to withdraw and seek backup.

When the drama cleared, a trail of destruction remained, with a severely battered Airbnb rental house at the heart of the damage.

View photos The rented home was damaged during the out-of-control party. Source: 7 News More

Pepper spray residue, blood splatter, graffiti and broken glass were left in the three-bedroom property, while some walls had holes kicked in them.

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