DES MOINES, Iowa -- Strong weekend Mega Millions ticket sales easily could push Tuesday's jackpot above last year's record $656 million prize, a lottery official said Sunday.

No ticket matched the six number needed to win Friday's $425 million prize. It was raised Saturday to $550 million for Tuesday's drawing -- the fourth largest in U.S. history.

Paula Otto, executive director of the Virginia Lottery and Mega Millions' lead director, told the Associated Press that sales were up by as much as 20 per cent in states that reported their weekend numbers. Sales were expected to spike on Tuesday, the day of the drawing.

"I think we'll be very close to the record, and maybe even surpass it," Otto said. "The challenging part in predicting is that so many of the sales happening on the day of the drawing.

"But lotto players are procrastinators. They tend to buy on the day of the draw."

As of Friday, players had bought enough tickets to cover roughly half of the 259 million possible number combinations, Otto said.