The Police Service of Northern Ireland arrested three men, including Jackson, 25 and Olding, 24, in June last year over the allegations reported to have taken place at a property in south Belfast.
The IRFU said the players strenuously deny the charges and have cooperated fully with police. Both players were "relieved of their duties" at club and national level until the matter is concluded, the union added.
"To allow the players time to address this matter fully Ulster Rugby and the IRFU have agreed that they be relieved of their duties and obligations until the conclusion of this process," the IRFU said in a statement.
Jackson has played 25 tests for Ireland, mainly as an understudy to British and Irish Lions flyhalf Johnny Sexton. Olding has represented his country four times at centre.
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(Reporting by Padraic Halpin; Editing by Christian Radnedge)
