Conor McGregor is under investigations in Spain after being accused of physically assaulting a woman last summer in Ibiza, court officials said Wednesday. 

Ultima Hora, a newspaper in Spain, released a report Tuesday with allegations from an Irish woman that the UFC superstar punched her and threatened to drown her at a party in July on his boat. 

The case had been closed, but a judge ordered it to be reopened after receiving more details about the alleged incident.

McGregor has denied the allegations.

"Mr. McGregor is steadfast in his denial of all the accusations made by a guest on his boat," McGregor spokesperson Karen Kessler told ESPN on Tuesday in a statement.

The unnamed woman initially told police immediately after the incident that it was not McGregor but another man who attacked her, according to reports from Spanish media at the time. Because she did not accuse him at that point, no case was opened in McGregor's native Ireland, per Ultima Hora, but now it will be investigated in Ibiza in light of the change in allegations by the woman.

McGregor celebrated his birthday July 16 at an Ibiza club, a party the woman said she attended, according to Ultima Hora. The woman said McGregor invited her into the VIP area and then onto his yacht with McGregor's girlfriend and friends, because he recognized her as someone he knew from his neighborhood in Dublin.

The next morning, the woman alleged that McGregor got surprisingly aggressive and violent with her out of nowhere, punching her in the stomach and chin, lunging at her and threatening to drown her. The woman jumped into the water to escape and was rescued by a Red Cross boat, per Ultima Hora.

According to Ultima Hora, the woman said that she didn't accuse McGregor initially because she was in shock, had nothing to wear but her bikini, had no money or phone and just wanted to return to her hotel in Ibiza as quickly as possible.

The court in Spain did not give any more detail about the case.