JERUSALEM, July 22 (Reuters) - The Israeli parliament gave preliminary approval on Monday to a bill that declares the main United Nations relief organization for Palestinians a terrorist organisation and proposes to sever relations with the body.

The vote against the United Nations Relief and Works Agency for Palestinian Refugees (UNRWA) is the latest step in a Israeli push against the agency, which Israeli leaders have accused of collaborating with the Islamist movement Hamas in Gaza.

The bill was approved in a first reading and will be returned to the foreign affairs and defence committee for further deliberation, the Knesset information service said.

The bill's sponsor, Yulia Malinovsky, was quoted as describing UNRWA as a "fifth column within Israel".

UNRWA provides education, health and aid to millions of Palestinians in Gaza, the West Bank, Jordan, Lebanon and Syria. It has long had tense relations with Israel but relations have deteriorated sharply since the start of the war in Gaza and Israel has called repeatedly for UNRWA to be disbanded.

"It's another attempt in a wider campaign to dismantle the agency," UNRWA spokesperson Juliette Touma said. "Such steps are unheard of in the history of the United Nations."

Israel has said hundreds of UNRWA staff are members of terrorist groups, including Hamas and Islamic Jihad, but has yet to provide evidence to a U.N.-appointed review.

Several donor countries halted funding to UNRWA following the Israeli accusations but many have since reversed the decision, including Britain which said last week it would resume funding.

Both Hamas and the Palestinian Authority condemned the Israeli vote, and Hussein Al-Sheikh, a senior ally of Palestinian President Mahmoud Abbas, called on the international community to resist attempts to dissolve the agency.

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