The allegations have rocked the Bible Belt university, known for its 60-foot bronze statue of praying hands, reports CBS News affiliate KOTV. Roberts, 58, said he would continue his role as chairman and CEO of Oral Roberts Ministries.
"I don't know how long this leave of absence will last, but I fully trust the members of the Board of Regents," Roberts said in a statement released by the university. "I pray and believe that in God's timing, and when the Board feels that it is appropriate, I will be back at my post as president."
An Oct. 2 lawsuit cites an internal report that says the Roberts allegedly remodeled their home 11 times in 14 years, used the university jet for personal trips, and forced members of the university to play an active role in a political campaign, something that is banned for non-profits such as the university, reports CBS News correspondent Hari Sreenivasan.
Three former ORU professors filed the suit and say they were forced out after turning over this information to the board of regents.
Their suit was amended last week to include new allegations that documents were shredded and destroyed days after the initial lawsuit was filed, and hours after ORU and Richard Roberts fired the school's comptroller.
The amended complaint also included an internal ministry report, titled "Scandal Vulnerability Assessment," documenting allegations of misconduct by the university and the Roberts family. Only a partial report was included in the Oct. 2 lawsuit. ( Read the "Scandal" document.)
The more detailed account alleges Richard Roberts' wife, Lindsay, spent the night in the ORU guest house with an underage male "on nine separate occasions," and was photographed 29 times with an underage male in her sports car, among other allegations.
The internal report was prepared by Stephanie Cantees, Richard Roberts' sister-in-law. An ORU spokesman said Cantees would not comment on the report.
An ORU student repairing Cantees' laptop discovered the document and later provided a copy to one of the dismissed professors.
In a statement, Lindsay said she lived her life in "a morally upright manner" and had never engaged in any sexual behavior with any man outside of her marriage as the accusations imply.
"The last three weeks have taken a serious toll on me and my family," Richard Roberts said in a statement Wednesday. "The untrue allegations have struck a terrible blow in my heart. The untrue allegations of sexual misconduct by my wife have hurt the most."
Gary Richardson, attorney for the dismissed professors, said his clients "stand ready and prepared at the appropriate time to prove the truth of those allegations, and also prove the truth of the fact they were fired after providing the information off Stephanie Cantees' computer to the board of regents.
"I want to know why they fired these guys," Richardson said.
Oral Roberts, 89, said last week that the allegations against his family had blindsided him, "but we have been through some tough experiences in building Oral Roberts University in the 1960s, and we have surprised them all and have built a university that we believe is for the glory of God."
The Roberts family ministry grew from Southern tent revivals to one of the most successful evangelical empires in the country, hauling in tens of millions of dollars in contributions a year. The university reported nearly $76 million in revenue in 2005, according to the IRS.
The elder Roberts founded the 5,300-student school, known for its 60-foot-tall bronze sculpture of praying hands, in 1963. He famously told viewers in 1987 that God told him to raise $8 million for the university or he would be "called home."
The week the lawsuit was filed, Richard Roberts said at a chapel service that God told him to deny the allegations. He said God told him: "We live in a litigious society. Anyone can get mad and file a lawsuit against another person whether they have a legitimate case or not. This lawsuit ... is about intimidation, blackmail and extortion."