GAZA, Aug 14 (Reuters) - Hamas on Sunday accused Palestinian President Mahmoud Abbas' Fateh movement of violating a reconciliation agreement by opening voter registration for local elections due to be held in October in the occupied West Bank.

Islamist Hamas, which seized the Gaza Strip in a 2007 civil war with Fatah, has described the planned ballot as illegitimate. Fateh is the dominant party in the Palestinian Authority, which exercises limited self-rule in the West Bank.

Hamas spokesman Sami Abu Zuhri said voter registration that opened in the West Bank on Saturday violated the agreement's call on both sides to avoid unilateral steps that could jeopardize the pact signed in Cairo in April.

Implementation of the accord has been held up by a disagreement between Hamas and Fateh over who would head an interim unity government in the run-up to presidential and parliamentary elections next year.

(Reporting by Nidal Almughrabi)