Celebrations are being held by Fatah in Gaza for the first time in five years
Hundreds of thousands of supporters of Palestinian leader Mahmoud Abbas's Fatah faction have held rallies in Gaza to mark the group's 48th anniversary.
Hamas, which governs Gaza, allowed rival Fatah to hold celebrations there for the first time since Hamas ousted Fatah forces five years ago.
Last month, supporters of Hamas celebrated their movement's founding with a rare rally in the West Bank.
The moves were aimed at easing tensions between the two sides.
Hamas came to power in Gaza after winning Palestinian elections in 2006 and ousting Fatah from the coastal enclave in clashes the following year, reports the BBC.
In a pre-recorded message played on giant screens, President Abbas said: "Victory is near and we will meet you in Gaza in the near future," AFP news agency reported.
"Gaza was the first Palestinian territory rid of [Israeli] occupation and settlement and we want a lifting of the blockade so that it can be free and linked to the rest of the nation," he said from his West Bank power-base.
Huge crowds, carrying the yellow flags of the Fatah movement and pictures of Abbas, streamed into Gaza City, the climax to a week of smaller celebrations across the strip marking Fatah's first attack against Israel.
Fatah officials said half a million supporters turned out. Hamas put the figure at 200,000.
Fatah organisers decided to end speeches early due to "the huge number of participants and logistical failures", Yahiya Rabah, a Fatah official in Gaza, was quoted by the Associated Press news agency as saying.
There were reports of clashes between rival Fatah factions, but none of violence between Hamas and Fatah supporters.
"The message today is that Fatah cannot be wiped out," Amal Hamad, a member of the group's ruling body, told Reuters news agency.
"Fatah lives, no-one can exclude it and it seeks to end the division."
Abbas and Hamas leader Khaled Meshaal signed a reconciliation deal in Cairo in 2011, but it has not been implemented.
In a speech during a visit to Gaza last month, Meshaal urged "reconciliation and national unity of the Palestinian ranks".
"Palestine is for all of us, we are partners in this nation. Hamas cannot do without Fatah or Fatah without Hamas, or any movement," he said.
Hamas, an Islamist movement, and the secular Fatah, fundamentally disagree in their approach towards Israel. Hamas has refused to renounce violence, recognise Israel's right to exist or accept peace accords between the Fatah-dominated Palestinian Authority and Israel.
Relations between Fatah and Hamas collapsed in June 2007 when Abbas ordered the dissolution of the Hamas-led unity government amid deadly clashes between the factions in Gaza. Hamas subsequently routed Fatah forces in Gaza and set up a rival government there.