Police investigating the Bulldogs rape case are expected to start taking DNA samples from players on Wednesday, threatening to overshadow the official league season launch the same day.

Meanwhile league chiefs expressed horror at suggestions the code encouraged or condoned a "gang-bang" culture, and pledged to stamp out any such activity.

Police said they would this week start DNA testing as part of investigations into allegations that Bulldogs players sexually assaulted a 20-year-old woman in Coffs Harbour.

National Rugby League chief executive David Gallop admitted the case would cast a shadow over the launch of the NRL season at a gala function in Sydney on Wednesday.

"Rugby league was going into a great season in 2004," Gallop said.

"It had a great season in 2003.

"There's no doubt this has cast a big shadow over our game as we go into the launch of our season."

Gallop also denied rugby league was promoting a "gang-bang" culture - a statement made in reference to an article in Sydney newspaper The Sun-Herald in which Bulldogs players gave their side of the story.

They claimed the woman involved in the incident in Coffs Harbour had sex with a number of players several days earlier, but not on the Sunday morning of the alleged sexual assault.

An unnamed player was quoted as saying: "Gang banging is nothing new to our club or the rugby league".

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