A gathering of Western and Arab powers plans to challenge Syrian President Bashar Al-Assad on Friday to provide humanitarian access within days to civilians under assault by his forces, US officials told reporters.
The officials, speaking before a "Friends of Syria" meeting expected to gather more than 70 nations and international groups in Tunis on Friday, did not say what specific consequences would follow if Syrian authorities failed to provide access.
"One of the things you are going to see coming out of the meeting tomorrow are concrete proposals on how we, the international community, plan to support humanitarian organisations ... within days, meaning that the challenge is on the Syrian regime to respond to this," said a US official.
The Syrian military pounded rebel-held Sunni-Muslim districts of Homs city for the 20th day on Thursday, despite international protest over the previous day's death toll of more than 80, including two Western journalists, activists said.
For more than a year, the Syrian opposition has called for Al-Assad, whose family has ruled Syria for four decades, to step down in the latest of the "Arab Spring" uprisings against authoritarian rulers in the Middle East.
The continued strife reflects both Al-Assad's determination to remain in office as well as the major powers' inability to agree on a strategy to ease, or force, him out.
Russia, which along with China has vetoed two UN Security Council resolutions on Syria, has said it would not attend the gathering in Tunis. China decided to boycott the meeting on Tuesday after Russia's decision to do so as well.
Russia has repeatedly said it does not want a resolution to become a pretext for regime change, something it believes took place when the Security Council authorised the use of force to protect civilians in Libya and that ultimately helped drive former dictator Muammar Gaddafi from power.
Asked if the group's call would amount to an ultimatum, a second US official told reporters: "It is a challenge."
The officials said Friday's meeting would focus on increasing humanitarian access, supporting the Syrian National Council opposition group in devising a transition plan, and coordinating sanctions.
"The point of this is to create increasing pressure on him as a result of the unity, as a result of a concrete proposal coming forward, and to put him in a position where the international community is demanding that he do the right thing," the second official said.
US Secretary of State Hillary Clinton, in London to attend an international conference on Somalia, met a number of her counterparts to discuss Syria, including the foreign ministers of France, Germany, Jordan, Morocco, Turkey, Saudi Arabia and the United Arab Emirates.
The US officials suggested the "Friends of Tunisia" group might not commit itself to a specific amount of aid for Syria on Friday, saying the fundamental issue was not money but access.
"I don't think resources are the problem. It is the access, the facilities that are needed, the conditions that are needed in order to allow that to be delivered," said the first official. "The constraint has not been on dollars."
They also avoided answering questions on whether the group may discuss the possibility of arming the opposition, something that some nations favour and that the United States, in a change in emphasis, on Tuesday suggested could become an alternative.
"The focus really is ... on what are the elements needed to respond to the tangible needs of the Syrians on the ground (and) that has to do with humanitarian access, and what is needed to promote a political transition," said the first official.
He said the group also wanted "to work with the opposition on implementing a pragmatic, practical transition plan that disproves Bashar Al-Assad's theory that the only alternative to him is chaos and civil war."