Republic of Ireland skipper Robbie Keane has questioned the refereeing decisions during his side's 3-1 loss to Croatia last night.

Keane was denied what looked like a clear penalty when he was brought down by Gordon Schildenfeld in the box with the score at 3-1.

At the time, Croatia had a man down at the other end of the field, causing the fans to boo Ireland for not kicking the ball out and the referee for not stopping the game, something that Keane believes had an impact on the ref's decision.

"I think so, yeah," he said, when questioned if he felt the two incidents were linked.

"It's definitely a penalty, there's no question about that. Their players and their fans were shouting for us to kick the ball out but, before the ball got to me, I think the fellow stood up or was just about to stand up.

"Whether the referee had that in the back of his mind, I'm not too sure. That's something you're going to have to ask him."

Ireland now face an uphill battle to qualify for the knock-out stages of the tournament, with their next match coming against reigning champions Spain on June 14.