GAZA, June 5 (Nidal al-Mughrabi/Reuters) - Islamist group Hamas stopped travelers from crossing into Egypt on Sunday in a row with Egyptian authorities over restrictions at the Rafah border that have dented Palestinians' hopes of ending Gaza's isolation.

Egypt eased border access last weekend to much fanfare, extending opening hours at the frontier and scrapping visa requirements for many Palestinians.

However, some Hamas officials say that Egypt appears to have had second thoughts and has since tried to slow the flow of Palestinians looking to leave the tiny coastal enclave.

On Saturday, the Egyptians unexpectedly shut the crossing altogether for previously unannounced maintenance work, sparking a small riot at the border.

Egyptian officials have denied any change to their policy and said the border was open again on Sunday. But Hamas border authorities kept the gates shut and demanded clarification from Cairo on the status of their transit agreement.

We have had contact with the Egyptian leadership. We want to hear from them whether the declared easing of travel restrictions are still in place, said Hatem Oweida, the Hamas head of crossings authority.

We need to know how many passengers can cross (each day) and we need our Egyptian brothers to speed up the processing of passengers through their side, he added.

Passengers returning from Egypt were allowed to cross on Sunday, officials said, but Gazans looking to leave were told by Hamas policemen that the exit was closed.

Egypt's interim military rulers have appeared keen to improve ties with the Palestinians and their announcement that they were relaxing Gaza controls was seen as a clear break from the policies of former President Hosni Mubarak.

Israel has tightened a blockade of Gaza since Hamas, which refuses to recognize the Jewish state, seized control in 2007, arguing that tough curbs were needed to prevent arms smuggling.

Mubarak helped Israel enforce the blockade and Israeli officials have made clear they think that more relaxed controls pose a security risk.

(Additional reporting by Yusri Mohamed in Egypt; editing by Crispian Balmer and David Cowell)