Tulisa Contostavlos celebrated her 25th birthday at Ocean Beach Club in Ibiza over the weekend. The British singer/songwriter is famous for being a member of N-Dubz. She has also appeared as a judge on the British version of "The X Factor."

The pop star looked amazing in a black bikini and chunky jeweled necklace. She was spotted partying with her friends and drinking what appeared to be champagne in the pool.

Last month, undercover journalists working for The Sun alleged she was caught on camera agreeing to arrange a cocaine deal. She was subsequently arrested on suspicion of supplying drugs.

Also in June, a man was arrested at her home in Hertfordshire, England, on suspicion of harassing her after he showed up at her property in the middle of the night.

But her recent troubles appeared to be behind her as she enjoyed her vacation in the Mediterranean Sea.

Check out more photos of Tulisa in a bikini...