Rockstar is "investigating" how and why copies of Grand Theft Auto 5 have arrived with some customers ahead of the game's official release, after requesting that online retailers do not dispatch copies until tomorrow, September 16.

Some customers received their copies of GTA 5 yesterday - four days in advance of the game's official street date - with other retailers across Europe reported to have been selling the title on the high street.

One French retailer is alleged to have advertised the fact that it is selling the game early on Facebook, while other reports suggest that the game is readily available in stores across Spain.

In a statement issued to GamesIndustry International this morning, Rockstar said that it is "in the process of investigating early 'sales' to determine how and why that is occurring."

Rockstar is thought to have placed strict guidelines on the sale of Grand Theft Auto 5, having requested that UK online retailers do not dispatch copies until the day before release.

It isn't yet known how the publisher will react to early sales or whether it will penalise Amazon for dispatching copies to customers early.

GTA 5 launches officially this Tuesday, September 17, with a PSN preload due to go live at 3pm this afternoon. Our review will be live on at 3pm BST tomorrow.

GAME says there's still time to secure a copy of GTA 5 for delivery tomorrow.