Britney Spears collapsed while hosting a nightspot's celebrity-studded New Year party.

The pop star was seen downing glasses of champagne before fainting.

Onlookers said the mother-of-two was carried from the building hidden under a hooded black poncho, screened by up to 12 bodyguards.

The drama happened at the Pure club, Las Vegas, which reportedly paid Spears £150,000 to appear.

The collapse followed heavy criticism suggesting Spears should cut back on wild nights out after splitting from husband Kevin Federline.

The 24-year-old, who has been out partying with hotel heiress Paris Hilton, was last night said to be 'fine" by manager Larry Rudolph.

He said: 'She had been travelling all day. She got really tired. It was a late night for her.'

One clubber said: 'It was crazy. Britney had been on the roof watching fireworks. She seemed to be having a really good time. But less than half an hour later, the club's security doors flew open. Britney's guards were trying to stop photographers taking pictures and shining torches in their eyes. She couldn't walk on her own.'

Spears and friends had earlier popped the cork on a £2,500 bottle of Dom Perignon champagne in front of a cake layered with Swarovski diamonds.

Celebrities at the bash included Desperate Housewives actor Jesse Metcalfe and his girlfriend, Girls Aloud star Nadine Coyle.

Spears recently promised to ease back on her partying. A message posted on her website admitted she had been 'burning the candle at both ends'.