The GAA are warning all supporters intending to travel to Sunday's All-Ireland semi-final and Tommy Murphy Cup final at Croke Park that tickets should only be purchased from official sources.

According to a statement released yesterday, "tickets purchased on the day from unofficial sources may already have been used to gain access to the stadium and those in possession of tickets that have already been scanned will not be permitted access to the ground".

All tickets for the triple-bill of games were issued to the participating county boards and GAA clubs for distribution, and resulted in an early sell-out. There was no general sale of tickets. The demand, however, comfortably outstripped the supply, with Dublin's allocation of just under 26,000 half of what was deemed necessary based on previous attendances this year.

The GAA also issued the latest request to supporters to allow plenty of time to gain access to the stadium, confirming that the Dublin-Mayo semi-final will start at 4pm sharp as scheduled. It will be preceded by the meeting of Leitrim and Louth in the Tommy Murphy Cup final at 2pm, and the All-Ireland minor football championship semi-final between Meath and Roscommon at 12.30pm.

Two of Dublin's games in Croke Park this summer have already been delayed because of the late arrival of supporters, but the GAA remain intent on ensuring that doesn't happen for a third time.

It was envisaged that by erecting barriers on the approach roads to Croke Park they could better regulate the flow of people up to the ground, but it was felt that would just lead to further congestion problems closer to the stadium.

Supporters travelling to Sunday's games were also asked to note that students and senior citizens in possession of tickets for the Davin (Canal End) and Cusack Stands are entitled to a €25 refund on production of valid ID from turnstiles at Block D Cusack Stand only, before entering the stadium.