A rogue referee has accused the world's top basketball league of rigging key games to boost ticket sales and television ratings.

Tim Donaghy made the incendiary claims against the American NBA in an attempt for leniency after pleading guilty to gambling on basketball games that he had refereed. The allegations appeared to be timed for maximum effect, coming only hours before Tuesday's game three of the NBA finals between the Los Angeles Lakers and the Boston Celtics.

“If the NBA wanted a team to succeed, league officials would inform referees that opposing players were getting away with violations,” Mr Donaghy's lawyer wrote to the court. “Referees then would call fouls on certain players, frequently resulting in victory for the opposing team.”

Donaghy's most serious charge is that league officials twice manipulated the NBA playoffs, the elimination phase of the annual competition. He alleged that two referees known to be “company men” rigged the 2002 playoffs between the Lakers and the Sacramento Kings to ensure that the best-of-seven series ran the maximum number of games.

The Kings needed a win in game six to clinch the series but, Donaghy claims, the referees ignored fouls against the Kings and awarded “made-up fouls” in the Lakers' favour to swing the match so that the series would go to a seventh game. Two Kings players —Vlade Divac and Scot Pollard — were sent off as they tried to defend against the Lakers star Shaquille O'Neal.

The Lakers won game six and game seven to win the series - and, ultimately, the championship - amid howls of protest and a call for an investigation from Ralph Nader, the consumer advocate and former presidential candidate.

Donaghy also accused NBA executives of instructing referees to target the Houston Rockets' 7ft 6in- tall star Yao Ming in a 2005 playoff series against the Dallas Mavericks. The alleged instruction had helped the Mavericks to rally from a 0-2 deficit to win the series, resulting in more tickets sold and more televised games”, Donaghy alleged.

The disgraced referee complained of “improper interactions” between umpires and team members. Some referees took autographs from players and merchandise from managers, he said, and one used a team's practice facility to exercise while another frequently played tennis with a team coach.

“Such inappropriate relationships could influence the outcome of games,” his lawyer said.

Donaghy is awaiting sentencing on July 14 after admitting that he bet on games at which he was officiating and provided coded tips to high-stakes gamblers for a $5,000 payoff. He could face up to 25 years in prison but is hoping for probation to reward his co-operation with prosecutors.

The NBA scoffed at his allegations. “He's a singing, co-operating witness who is trying to get as light a sentence as he can,” David Stern, the NBA commissioner, said. “He turned on basically all of his colleagues in an attempt to demonstrate that he is not the only one who engaged in criminal activity.

“The US Attorney's office, the FBI, have fully investigated it, and Mr Donaghy is the only one who is guilty of a crime. And he will be sentenced for that crime, regardless of the desperate attempts to implicate as many people as he can.”

Phil Jackson, the Lakers coach, who has led nine NBA championship-winning teams, has called for referees to be put under an outside entity separate from the league.

Dirty tricks

— According to Greek myth, the Olympic Games have their origins in match-fixing. The poet Pindar wrote that Peplos accepted a chariot race to win the king's daughter, but bribed the charioteer to replace his linchpin with one of wax. The Games were established to celebrate his victory

— The earliest recorded case of match-fixing occurred in 1900. Jack Hillman, the Burnley goalkeeper, is alleged to have offered the Nottingham Forest side £2 a head to “take it easy”. The offer was raised to £5 at half-time. Burnley lost 4-0

— Porto were excluded this month from next season's Champions League after the lengthy “Golden Whistle” investigation into the alleged bribery of referees in the 2003-04 season

— In 2006 the Italian clubs Juventus, Lazio and Fiorentina were demoted to the second division and banned from playing in Europe for their involvement in a match-fixing scandal. After several appeals only Juventus went down, while the others, plus AC Milan, had points deducted

— This year China's badminton head coach admitted fixing the 2004 Athens Olympics semi-final. Zhou Mi was asked to let her Chinese rival win because Zhang Ning stood a better chance in the final

Sources: Penn Museum; arsenalinsider.co.uk; Times archives