Western and Arab nations will demand Friday that Syrian President Bashar al-Assad halt his 11-month-old crackdown on the opposition and allow aid to be delivered to desperate civilians trapped by the escalating violence.

With little sign of any international resolve to intervene to end the violence, Syria's opposition appeared to be taking matters into its own hands, saying it was supplying weapons to rebels inside Syria while Western and other states turned a blind eye.

Foreign ministers from more than 50 countries were in the Tunisian capital for the Friends of Syria inaugural meeting, against the backdrop of a surge in government attacks on the city of Homs and mounting world outrage over violence that has killed thousands of people during the uprising.

Delegates said that with efforts to end the violence through the United Nations blocked by Russia and China, the aim of the meeting was to challenge Assad to let in aid and to lay the groundwork for an eventual handover of power in Syria.

Confronted by the crimes committed against humanity, it is the duty of the international community to reinforce the pressure on the Syrian regime, French Foreign Minister Alain Juppe told the meeting.

Bashar al-Assad has taken the terrible decision to drown the aspirations of his own people in blood. He therefore carries a heavy responsibility before history.

A diplomat attending the conference said the objective was to persuade groups not yet convinced of the need for Assad to step down, including Russia, China and Syria's business community, that they were backing the wrong side.

The point is to make the transition look more inevitable, said the diplomat.

ARMS SUPPLIES

Highlighting the limits of diplomacy to end the violence so far, a source with the Syrian National Council, the main opposition grouping, said arms were already being ferried to rebels fighting Assad's forces inside Syria.

We are bringing in defensive and offensive weapons ... It is coming from everywhere, including Western countries and it is not difficult to get anything through the borders, the source told Reuters in Tunis, speaking on condition of anonymity.

There is not a decision by any country to arm the rebels but countries are allowing Syrians to buy weapons and send them into the country.

The Friends of Syria were unlikely to publicly endorse the supply of arms because their public position is that they want a negotiated solution.

Equally, there was no sign they would try to stop the supplies, seen in many capitals as an unavoidable result of the United Nations' failure to take firm action after Russia and China vetoed draft resolutions on Syria.

A crowd of several hundred Assad supporters tried to force their way into the venue of the meeting, a seaside hotel in a suburb of Tunis, minutes before the session was scheduled to begin. They were held back by Tunisian security forces.

A draft of the declaration to be issued at the meeting called on Syria to immediately cease all violence to allow the United Nations access to Homs, and to let agencies deliver aid to civilians affected by the violence.

The Friends of Syria pledged, in the latest version of the draft seen by Reuters, to deliver humanitarian supplies within 48 hours if Syria's government stopped its assault on civilian areas and permitted access.

Assad's government appears reluctant to allow foreign aid in. The International Committee of the Red Cross has for days been trying to negotiate access for relief supplies but said it had received no reply to its request from Damascus.

A senior member of the opposition Syrian National Council said it would take pressure from Russia - Assad's closest big-power ally - to force the Syrian leader to comply.

I think there is only one option which has not been fully explored and that is the Russians forcing the regime to allow humanitarian access. That is the only option I see, said Basma Kodmani.

In a sign the international community is seeking ways around the Security Council deadlock, U.N. Secretary General Ban Ki-moon said he would dispatch former U.N. chief Kofi Annan to Syria as a joint U.N.-Arab League envoy.

HARSH REALITIES

The draft Friends of Syria communique did not mention any foreign military intervention along the lines of the NATO bombing campaign that helped force out Libya's Muammar Gaddafi.

Instead, it called for further diplomatic pressure on Assad to step down and endorsed an Arab League plan that would see him handing power to a deputy as a prelude to elections.

The group will also commit to enforce sanctions aimed at pressuring the Syrian authorities to halt violence, according to the draft declaration.

These include travel bans, asset freezes, a halt to purchases of Syrian oil, ceasing infrastructure investment and financial services relating to Syria, reducing diplomatic ties and preventing arms shipments to the Syrian government.

Juppe said the European Union would freeze the assets of Syria's central bank from Feb 27.

The wording of the draft reflected a harsh reality: there is little the outside world can or will do to stop the violence as long as Russia and China, both of which declined invitations to the Tunis meeting, reject Security Council resolutions.

Divisions within the Syrian opposition pose another problem for world powers, who will seek to overcome them before offering full backing.

The draft stopped short of fully endorsing the Syrian National Council as the sole legitimate representative of the Syrian people but proposed that it be recognized as a legitimate representative of Syrians seeking peaceful democratic change.

(Additional reporting by Dominic Evans in Beirut, Lou Charbonneau at the United Nations, Arshad Mohammed, Tarek Amara and John Hemming in Tunis; Writing by Lin Noueihed and Christian Lowe; Editing by Janet Lawrence)