In an interview with Times Online, GTA IV producer Leslie Benzies has confirmed that the budget invested in the new Rockstar’s title was approximately $100 million.

Benzies said that a team of 1,000 people was involved in the creation of the game in the past three and a half years.

During this period Benzies and other key members of the team have been working 12-hour days.

“You have to be focused on it 100%,” he said for Times Online. “There is no time or space to do anything else. Most of the people here love what they do. It's like playing in a band.”

Rockstar refused to disclose the figures about the game sales in its first day of availability, but ChartTrack, the official UK gaming industry monitor, said GTA IV is the fastest selling game ever in UK in a 24 hour period.

In its first day of availability, Rockstar’s GTA IV sold 609,000 units, surpassing the previous record held by none other than GTA: San Andreas. Back in 2004, GTA: San Andreas sold 501,000 copies in its first day.

ChartTrack also revealed that 335,000 copies were sold on Microsoft’s Xbox 360. Halo 3, released last year in September exclusively in Xbox 360, sold 266,000 units in its first day.

Sony’s PS3 scored its own record, because GTA IV sold 274,000 copies on PS3, outselling the previous record holder, Gran Turismo 5: Prologue, which sold 80,000 units in its first day. ChartTrack will release the figures for the whole week next Tuesday.

Analysts forecasted that more than six million copies of the game will be bought worldwide during the first week of sale.

The Take Two officials are optimistic about the game’s financial potential. Speaking with Reuters, Take-Two's CEO Ben Feder said the company’s expectations are “higher than analysts give the game credit for”.

"All the analysts had a (sales) number, give or take, and I think we will be on the upside of that rather than the downside,” he said. The analysts have forecasted that the game will sell nine million units until the end of the financial year.