Madonna has threatened to cancel her infant son's baptism in a Scottish cathedral tonight out of fear a growing army of reporters will spoil it.

In a closed-door meeting with cops, the Material Mom said the planned baptism of 4-month-old Rocco — 24 hours before she's to marry his dad, Guy Ritchie — is turning into a media circus. 

More than 500 journalists have raided the tiny town of Dornoch for tomorrow's $2 million wedding at Skibo Castle — and another 200 are expected today. 

Madonna had hoped to kill two birds with one stone by having Rocco baptized at Dornoch Cathedral as her superstar celebrity pals, including Gwyneth Paltrow, Sting and Rupert Everett, watch. 

But as the media crush grew outside the cathedral, Madonna told officials she'll "cancel the baptism if things look likely to get out of control," the BBC reported. 

Madonna's security team, 200 strong, is said to have hired 50 extra people to keep reporters at bay. 

There are also worries either a guest or employee at Skibo Castle will secretly videotape the wedding with a miniature camera or record it for a bootleg CD. 

As a result, guests will be checked as they enter, special mirrors will be used to look under kilts, and everybody working the wedding will be subjected to random frisks. 

"Madonna's bodyguards are a hard-bitten bunch. They think this idea is a hoot and are calling themselves the Sporran Legion," one castle insider said, referring to the leather pouch Highlanders wear on their dress-costume belts. 

If the baptism goes off as planned, Sting will sing a special song for Rocco, and Madonna will warble "Ave Maria." 

Other big names tipped to attend include heartthrob George Clooney, Robin Williams and Brad Pitt. 

Madonna's kid sister Melanie, 36, arrived yesterday with her record-producer hubby, Joe Henry, who first told reporters he was rocker Tom Petty and then said he was Brad Pitt. 

Ritchie's bachelor party will be held today in the local village hall. Dozens of cartons of whisky, champagne and beer were delivered there yesterday. 

Meanwhile, the British bookmaker Ladbroke's has issued odds on the wedding. It's given even money for the groom to defy convention and wear pants under his kilt, while the pop goddess is 5-1 to wear black.