Kim Kardashian flashes her bright red G-string as the wild festivities...

Kim Kardashian proudly displayed the string of her underwear as she posed for a sultry photo series during the early birthday celebrations.

The Keeping Up With The Kardashians star turns 40 on Tuesday and the celebrations appear to be four more days.

The mother of four took to Instagram on Friday and posed in a backless black dress designed by Matthew Williams while she slipped a giant statement handbag across her arm.

The design of the dress included a huge round neckline at the back – with Kim drawing attention to her famous bum when she wore a bright red G-string poking out through the gap in the fabric.

The famous reality star appeared to be doing a stripper drop dance move when a photographer snapped. One picture showed her close to the ground with her hair swirling around.

While a third snap showed her peering over her shoulder as hair extensions went down to her infamous derrière, the brunette curls licked the top of her underwear.

Kim also went to Instagram Stories to show off a new dress designed and inspired by Alexander Wang.

The star wore the shimmering crystal outfit with her own body in a pink bikini.

Self-promotion for photos and videos came hours after the star shared a video of herself breaking out of a giant birthday cake.

The star had been ripped from the top of a giant cake in an eccentric birthday photo shoot before her birthday next week.

The reality TV star went into fashion and makeup mogul kicked off the party weeks earlier when she attended a special photo shoot to mark her milestone.

Despite her years, Kim looked flawless and completely wrinkle-free as she smoldered into the camera.

As it appeared as a candle, it emerged from a huge homemade cake.

The 39-year-old even looked glamorous as she positioned herself awkwardly to showcase her wealthy assets in a tiny silver bikini on camera.