Palestinian pilgrims bound for Mecca were prevented from leaving the Gaza Strip via Egypt on Saturday.
The pilgrims, hoping to reach Saudi Arabia next week for the annual haj pilgrimage, told Reuters that Hamas police set up checkpoints 300 metres from the Rafah border post with Egypt and turned them away.
Hamas security also barred journalists from the border area of the town of Rafah.
Hamas officials blamed Egypt, saying it had not opened the border as agreed. The Egyptian Foreign Ministry and witnesses in Rafah said Egypt opened the crossing point for the pilgrims on Saturday but none came.
At Rafah, a 60-year-old pilgrim who gave his name as Abu Abdullah said: "I am not with Fatah and not with Hamas. I wanted to worship God and to go on the haj before I die. Sadly, the schism has now spilled into our religion."
The root of the problem appeared to lie in disputes between the two main Palestinian factions, Hamas and Fatah, which each controls one of the two Palestinian territories, and also involves Saudi Arabia's policy on issuing visas to Palestinians.
Saudi Arabia says it has granted visas only to Palestinians who registered for the haj through the Palestinian Authority, controlled by President Mahmoud Abbas's secular Fatah faction in the West Bank. Some 3,000 people in Gaza have done so.
A further 3,000 Gazans have tried to arrange visas through Hamas, which seized control of the enclave last year.
Hamas is appealing to Saudi Arabia to relent and give them visas. Some Hamas leaders have said that unless it does so, they will prevent anyone leaving Gaza for the pilgrimage to Mecca.