The Palestinian Authority has signed up formally to the Geneva Conventions, which set down the rules of warfare and humanitarian operations in conflict zones.
Swiss foreign ministry spokesman Pierre-Alain Eltschinger told AFP that the Palestinian Authority had declared itself party to the conventions on 2 April.
It was registered formally by the treaties' guardian Switzerland yesterday, he added.
The step is part of a new diplomatic drive by Mahmoud Abbas, the Palestinian President, coming as peace talks with Israel are close to collapse.
The Palestinians had pledged to freeze all moves to seek membership in UN organisations and international conventions.
This was a stepping stone to recognition of their hoped-for state, during the talks in return for Israel's release of veteran Arab prisoners.
Israel has meanwhile made a new attempt to expand settlements in Arab east Jerusalem.
The Fourth Geneva Convention states "the Occupying Power shall not deport or transfer parts of its own civilian population into the territory it occupies".
The original Geneva Conventions were crafted in the 19th Century under the auspices of the Swiss-based International Committee of the Red Cross and recast after World War II.
Over the subsequent decades, optional protocols were added to take into account the developing realities of war and its impact on civilians.
The Palestinians have also submitted requests to the United Nations to join 13 other international conventions and treaties.
The treaties include the Vienna Convention on diplomatic relations, the convention on the rights of the child, the convention against torture, and an anti-corruption accord.