New York- A self-proclaimed minister tried to blackmail Gary Sheffield over alleged threesome sex tapes featuring the Yankee slugger’s gospel-singer wife, another woman and R&B star R. Kelly, the player’s rep and sources said yesterday.

Rufus Williams, the outfielder’s business agent, revealed stunning details of the reputed plot to shake down his client for at least $20,000 to keep the raunchy tapes from surfacing and embarrassing the devoutly religious Sheffields.

The alleged footage of Sheffield’s 28-year-old wife, DeLeon, Kelly, 36, and the unidentified other woman was said to have been made more than 10 years ago.

In a statement, Sheffield said only that his wife – a child gospel star who didn’t let him kiss her for the first seven months of their courtship – had had a long relationship with a musician.

He said he knew about the relationship, which occurred well before their wedding in 1999.

“I have not seen the alleged videotape, nor do I care to,” the slugger said. “I love my wife, and I vow again to stand by her through any trial or tribulation.

“I will not be blackmailed,” Sheffield added. “I will not have my family dragged through the mud and filth.”

Williams said the shakedown attempt began when he received a phone call Nov. 3 from Chicago activist Derrick Mosley. He said Mosley told him he had received two tapes in the mail with no return address, according to an FBI affidavit.

Mosley, describing the explicit footage as “very repulsive,” said “he was very upset and concerned about the tapes” and he “wished to speak to Individual A about reform and her moral standing,” the affidavit said.

Williams said he contacted the FBI and began secretly taping their conversations.

At one point, Mosley reportedly urged Williams to hire him for $20,000 to counsel Sheffield’s wife – and as assurance that he would have the tapes destroyed.

“Someone else would have called the tabloids and could have made millions,” Mosley told Williams, according to the affidavit.

The scheme came to a head on Nov. 11, when Mosley accused Williams of stalling and demanded the $20,000 immediately, the affidavit said.

Mosley, 38, was arrested at home Monday and charged with attempted extortion.

He was in jail pending a bond hearing tomorrow. His lawyer did not immediately comment on the charges. Mosley claims to be a minister and has acted as a spokesman for families of victims of last year’s E2 nightclub stampede.

But he also has a police record, having pleaded guilty to bank fraud in 1999. He was sentenced to one year in jail and received five years’ probation. He also was allegedly involved in a previous, unrelated extortion attempt involving Kelly. In a statement, Kelly’s spokesperson denied knowledge of the tape.

“Since we haven’t seen the tape, we can neither confirm nor deny that it is in fact Mr. Kelly. We can, however, confirm that no one is suggesting the tape depicts anything but the activities of consenting adults.”

Kelly has seen his own share of troubles.

He has pleaded not guilty in a pending kiddie-porn case.

He also just sued rapper and former tour mate Jay-Z after stalking off the stage claiming he was being threatened by someone with a gun, only to be allegedly pepper-sprayed by a member of Jay-Z’s entourage.

Sheffield’s reps said he was out of the country.

A self-proclaimed minister tried to blackmail Gary Sheffield over alleged threesome sex tapes featuring the Yankee slugger’s gospel-singer wife, another woman and R&B star R. Kelly, the player’s rep and sources said yesterday.

Rufus Williams, the outfielder’s business agent, revealed stunning details of the reputed plot to shake down his client for at least $20,000 to keep the raunchy tapes from surfacing and embarrassing the devoutly religious Sheffields.

The alleged footage of Sheffield’s 28-year-old wife, DeLeon, Kelly, 36, and the unidentified other woman was said to have been made more than 10 years ago.

In a statement, Sheffield said only that his wife – a child gospel star who didn’t let him kiss her for the first seven months of their courtship – had had a long relationship with a musician.

He said he knew about the relationship, which occurred well before their wedding in 1999.

“I have not seen the alleged videotape, nor do I care to,” the slugger said. “I love my wife, and I vow again to stand by her through any trial or tribulation.

“I will not be blackmailed,” Sheffield added. “I will not have my family dragged through the mud and filth.”

Williams said the shakedown attempt began when he received a phone call Nov. 3 from Chicago activist Derrick Mosley. He said Mosley told him he had received two tapes in the mail with no return address, according to an FBI affidavit.

Mosley, describing the explicit footage as “very repulsive,” said “he was very upset and concerned about the tapes” and he “wished to speak to Individual A about reform and her moral standing,” the affidavit said.

Williams said he contacted the FBI and began secretly taping their conversations.

At one point, Mosley reportedly urged Williams to hire him for $20,000 to counsel Sheffield’s wife – and as assurance that he would have the tapes destroyed.

“Someone else would have called the tabloids and could have made millions,” Mosley told Williams, according to the affidavit.

The scheme came to a head on Nov. 11, when Mosley accused Williams of stalling and demanded the $20,000 immediately, the affidavit said. Mosley, 38, was arrested at home Monday and charged with attempted extortion.

He was in jail pending a bond hearing tomorrow. His lawyer did not immediately comment on the charges. Mosley claims to be a minister and has acted as a spokesman for families of victims of last year’s E2 nightclub stampede.

But he also has a police record, having pleaded guilty to bank fraud in 1999. He was sentenced to one year in jail and received five years’ probation. He also was allegedly involved in a previous, unrelated extortion attempt involving Kelly. In a statement, Kelly’s spokesperson denied knowledge of the tape.

“Since we haven’t seen the tape, we can neither confirm nor deny that it is in fact Mr. Kelly. We can, however, confirm that no one is suggesting the tape depicts anything but the activities of consenting adults.”

Kelly has seen his own share of troubles.

He has pleaded not guilty in a pending kiddie-porn case.

He also just sued rapper and former tour mate Jay-Z after stalking off the stage claiming he was being threatened by someone with a gun, only to be allegedly pepper-sprayed by a member of Jay-Z’s entourage.

Sheffield’s reps said he was out of the country.