GAZA, June 12 (Reuters) - The Western-backed Palestinian Fateh faction on Sunday expelled a former leader, once seen as a possible successor to President Mahmoud Abbas, the official WAFA news agency said, exposing divisions in the ruling movement.

The ousting of Mohammed Dahlan, for years Fateh's strong-man in the Gaza Strip, and the splits it has revealed, could damage the movement's standing in unity talks with its rival faction, Islamist Hamas.

The Fateh Central Committee has decided to dismiss Mohammed Shaker Dahlan and end any official connection of his to the movement ... It has also decided to refer him to the judiciary over criminal and financial cases, part of the statement said.

Fateh's influential Central Committee met at its West Bank power base in Ramallah on Saturday and published its decision on Sunday night.

Movement officials speaking anonymously have accused Dahlan of trying to undermine Abbas and of illicit financial dealings.

Dahlan first fell from grace in 2007 when Hamas Islamists routed Fateh forces to take control of the Gaza Strip where he still has a power base. As security chief he had been charged with keeping Fateh dominant in the coastal territory.

Palestinian officials, speaking anonymously, have said Dahlan in the past publicly slurred Abbas's sons and criticized the Palestinian president, going as far as calling for his replacement.

Dahlan confidants said he could now further inflame his row with Abbas by speaking publicly on the dispute.

He has lots to say about the Fateh Central Committee and Abu Mazen (Abbas) personally, one aide said.

(Reporting by Nidal al-Mughrabi, writing by Ori Lewis; Editing by Andrew Heavens)