US rapper Nelly is being investigated by Essex Police. Getty Images

US rapper Nelly is under investigation by Essex police after a woman claims she was sexually assaulted by the star after a gig in Southend.

The St Louis, Missouri, native allegedly sexually assaulted a fan on 5 December after she asked him for a photo following his performance at Cliffs Pavilion, in Westcliff-on-Sea.

The Hip-Hop star, real name Cornell Iral Haynes Jr., was defended by his lawyer Scott Rosenblum who dismissed the allegations as untrue and "not new".

Essex police in a statement said: "We are investigating after a woman reported to us that she was sexually assaulted at an address in Westcliff on December 5, 2017. Enquiries are ongoing."

The 43-year-old shot to fame in 2000 with his album 'Country Grammar' following with 'Nellyville' and 'Suit' which were all hit number one records on the Billboard charts.

Rosenblum , an attorney for Nelly, told Mirror Online: "Nelly welcomes a thorough investigation. Nelly is confident that once investigated, these claims will be determined to be disingenuous.

"Nelly was accompanied by his girlfriend during this tour and she was at his side throughout. It is important that police investigate every allegation of this nature."

The woman was quoted by US entertainment website saying that Nelly placed his arm behind her and asked if she could stay behind to talk to him.

"They went to his dressing room with her friends and she says he then asked her to come to a room next door,' the website said.

"She claims once in the room he dropped his pants and began masturbating in front of her. She also claims he put his hand on her top and tried pulling it off. She says he also tried kissing her as she tried to bolt from the room."

It was reported that Nelly then forced her head down towards his crutch before she left the room and he swore at her as she left.

In October last year Nelly a 21-year-old woman who originally claimed she was sexually assaulted on his tour bus in Washington dropped charges against him.

Nelly has sold more than 22 million albums and had four number one singles with Hot In Herre, Shake Ya Tailfeather, Grillz, and Dilemma, featuring Kelly Rowland.