Amnesty International called on Friday for an immediate arms embargo on the Syrian government and for caution over the supply of weapons to rebels in the conflict-strewn country.
On the eve of a "Friends of Syria" meeting in Paris, Amnesty urged "the imposition of an immediate arms embargo aimed at stopping the transfer of arms to the Syrian government."
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And "amid growing reports of abuses by members of the armed opposition, states should also stop arms transfers to the opposition wherever there is a substantial risk that they are likely to be used for war crimes or other human rights abuses."
Ann Harrison of Amnesty's Middle East and North Africa department said: "We expect the Friends of Syria to leave this meeting in France with a clear plan to end crimes under international law and ensure justice, truth and full reparation for victims."
The organisation also said that "any peace plan on Syria must exclude the possibility of amnesties or similar measures being issued for crimes under international law."
France on Friday is to host a third Friends of Syria meeting aiming to coordinate Western and Arab efforts to stop violence in the country that monitors say has cost more than 16,500 lives since March 2011.