Saints Row: The Third PS3 version offers free copy of Saints Row 2

The mystery of the missing PlayStation 3 exclusive content has been solved.

On the US PS Blog, Sony has announced every new PS3 copy of Saints Row: The Third entitles the purchaser to a free copy of Saints Row 2.

The free game is offered via the bundled online pass, and will become available next week for those who have already redeemed it.

The offer is only valid for 90 days, expiring on February 13, 2012. Saints Row 2 normally goes for $20 on the US PSN.

We've asked THQ whether the offer will be extended to territories outside the US. Expect an update as soon as we know more.

The PS3 version of the game had been expected to include and exclusive multiplayer mode, but early players were puzzled to find it contained no extra content when the game released on the three major platforms this week.