Trevor Brennan and Gareth Thomas have been called to appear before an independent disciplinary committee in Dublin on 1 February.
The Toulouse players face misconduct complaints following the controversial Heineken Cup clash against Ulster last Sunday.
Brennan, the Toulouse lock, is charged under Heineken Cup disciplinary rules with allegedly entering one of the seating areas and assaulting an Ulster supporter.
Thomas is alleged to have engaged in 'aggressive exchanges with spectators' and/or 'aggressively attempted to enter one of the seating areas' and/or 'made an offensive hand gesture towards spectators'.
The panel will be chaired by Jeff Blackett, the Rugby Football Union's disciplinary chief, and will also comprise Rod McKenzie (Scotland) and Achille Reali (Italy).
If Thomas is found guilty and handed a ban it will rule him out of Wales' opening RBS 6 Nations clash with Ireland on 4 February.
Brennan is alleged to have punched Ulster supporter Patrick Bamford several times, leaving the 25-year-old accountant requiring medical treatment at the ground and on his return home to London.
The former Ireland international claimed he had been provoked by derogatory chants about his mother.
In a statement released earlier this week he said: 'When I was warming up, I heard a group of supporters sing: 'Brennan, your mother is a whore'.
'One of them looked me in the eyes, and again started to sing `Brennan, your mother...'.
'I then climbed the wall and had an altercation with this person.
'I regret this incident. But I didn't initiate it. That is the last thing I wished to do.
'I love rugby, I love Toulouse and the supporters, but I love my family and my mother more than all that.'
Toulouse launched a robust defence of Brennan, describing the 33-year-old as a 'generous man who has always respected opponents and their supporters'.
The French club added: 'It required sustained and repeated provocation to make him react in an unacceptable but understandably human way.
'We want European Rugby Cup (ERC) to investigate the behaviour of some of the Ulster supporters.'
But Bamford categorically denied abusing Brennan's mother and maintains he was poking fun at the bar the player runs in Toulouse.
'I categorically deny that at any point that I or anyone sitting around me was involved in sectarian abuse or in abuse of Mr Brennan about his mother,' Bamford said in a statement.
'This recollection of events has been supported by witness statements taken at the time.'
Ulster have submitted a report of the incident to ERC after receiving written statements and photographs from eye-witnesses.
