Austria has warned its 26 European Union partners in a letter against providing weapons for rebel movements in the Syrian conflict, said a press report to be published Tuesday.

The foreign ministry in Vienna confirmed late Monday that a document had been handed over to the European Union in Brussels, but did not give details.

Die Presse newspaper said that Austria believes arms shipments to the rebels fighting Syrian President Bashar al-Assad would be "a violation of international law, the basic laws of the European Union" and "of the principles of the United Nations charter concerning non-intervention and the use of force".

They would also violate UN Security Council resolutions concerning Al-Qaeda, it said.

In the letter Austria warned that groups like the Al-Nusra Front, which is "close to the terror network", were acting among the rebels, Die Presse said.

Following a move by France and Britain, the Islamist group, which has become one of the most feared fighting forces in Syria's two-year-old conflict, will be subject to a global asset freeze from Tuesday.

European Union sanctions against Syria are up for renewal at the end of the month, with France and Britain pushing for a lifting of the arms embargo so the rebels can receive weapons.

Die Presse said the letter warned that a lifting of the arms embargo would also lead to an end of all sanctions which can only be extended unanimously by all 27 EU members.

Those who lift the embargo would then also be responsible for unfreezing Assad's foreign bank accounts, it said.

Finland, Sweden and Baltic nations Estonia, Latvia and Lithuania are also opposed to lifting the embargo, while most other EU nations, including Germany and Spain, have so far failed to clarify their positions.