A statement from Ulster Rugby made clear the men maintain their innocence.
'Paddy Jackson and Stuart Olding have been assisting the PSNI (Police Service of Northern Ireland) with inquiries,' it said.
'The players deny any wrongdoing and have not been charged with any offence. As no charges have been brought forward, it would be inappropriate to comment further.'
A separate statement from Jackson's lawyers, KRW Law, said: 'He rejects completely any allegations made against him. Patrick has co-operated fully with police in their inquiries and we have been liaising with police on his behalf.
'We are both disappointed and indeed concerned that this information has been leaked to the press before the investigation has concluded and well in advance of any final decision.
This has the potential to be prejudicial to our client's interests.
'We will not hesitate to take all necessary steps to protect his legal position as he is entitled to the presumption of innocence. We urge the media to restrain from any damaging speculation.'
Jackson was not included in Ireland's 27-man squad travelling to Chicago to play New Zealand on Saturday. The Irish Rugby Football Union (IRFU) said the out-half was left out of the party for 'personal reasons'.
Olding is currently out of action with a hip flexor injury.
Jackson, 24, has been capped for Ireland 16 times while centre Olding, 23, has played four times. The two Belfast men are established stars for Ulster Rugby and have played regularly this season.
The Police Service of Northern Ireland (PSNI) said: 'Police arrested two men aged 24 and one man aged 23 on Thursday 30 June in relation to a number of sexual offences, reported to have taken place at a property in south Belfast on 28 June.
'The men have been interviewed and released from custody. A file will be prepared for submission to the Public Prosecution Service (PPS). A fourth man aged 24, will be reported to the PPS in relation to this incident for perverting the course of justice.'
