James Loxton agreed a move to Connacht from Cardiff Blues
New Connacht signings Matthew Jarvis and James Loxton appear ineligible to play for Ireland under current International Rugby Board regulations.
The revelation has come as a major surprise to Connacht officials who signed the duo on the basis that they were Irish-qualified.
Both have played for the Wales U20s - the country's designated second team.
Players who take part in a match for a country's second senior side are not normally allowed to change allegiance.
However, the players and Connacht believed that they were Irish-qualified because they have not represented either Wales A or the Wales Sevens team.
Welsh RFU officials noticed the qualification anomaly when they saw Connacht's press release about the signings on Monday and informed the Irish province on Tuesday.
Connacht officials have contacted the IRFU and the Irish governing body is believed to have sought clarification from the IRB on the matter.
If the IRB confirms that the two men are not Irish-qualified, their moves to Connacht are likely to be put in doubt.
Jarvis, who can play at 10, 12 or 15, has been playing for the Ospreys, while utility back Loxton has been signed from the Cardiff Blues.
"I've enjoyed my time with Cardiff but once I had the opportunity to play for Connacht in Ireland, it was one I couldn't refuse," said Loxton.
"Connacht have big plans for the future and I want to be part of that vision."
Added Loxton: "They play an open, expansive and exciting brand of rugby which will suit my game as a wing/full-back.
"My mother was born in Crossmolina, County Mayo, I go on holiday there every summer and I'm delighted at the prospect of playing professional rugby where my ancestors were born and bred."