LONDON -- The United States, Europe and Arab nations crafted a stern warning to Syrian President Bashar Assad Thursday : Agree to an immediate cease-fire and allow humanitarian aid into areas hardest hit by his regime's brutal crackdown on opponents, or face as-yet unspecified punishments.

U.S., European and Arab officials met in London to work out details of an ultimatum to Assad. Diplomats said it would demand immediate compliance or there would be additional punitive measures, likely to include toughened sanctions. The ultimatum is to be presented at a major international conference on Syria Friday in Tunisia.

A draft of the document obtained by The Associated Press calls on "the Syrian government to implement an immediate cease-fire and to allow free and unimpeded access by the United Nations and humanitarian agencies to carry out a full assessment of needs in Homs and other areas." Homs has been under a fierce government attack for nearly three weeks.

The draft, still subject to change, also demands "that humanitarian agencies be permitted to deliver vital relief goods and services to civilians affected by the violence." More than 5,400 people have been killed in the nearly year-old uprising.

Meanwhile, Tunisia's presidential spokesman, Adnan Mancer, said in an interview ahead of today's meeting that Tunisia will propose a political solution to the crisis that includes the deployment of a peacekeeping force and Assad stepping down from power.

The political transition would be akin to what happened in Yemen, where President Ali Abdullah Saleh stepped down in favor of his deputy after widespread protests. The Arab League already has made similar calls on Assad.

American officials accompanying Secretary of State Hillary Rodham Clinton to the Tunis meeting of the "Friends of Syria" said the group hoped to make clear to Assad that his regime has a moral obligation to end the shelling of civilian areas and allow assistance into the country.

In Homs, where shelling of Baba Amr killed correspondent Marie Colvin, an East Norwich native, and French photographer Remi Ochlik on Wednesday, reporter Edith Bouvier of Le Figaro was shown in a video posted on YouTube pleading to be evacuated so she can have an operation. She said her leg is broken in two places. Sunday Times photographer Paul Conroy was also wounded.

From celebrating America's 250th birthday to a new ride at Adventureland, NewsdayTV's Elisa DiStefano and Newsday lifestyle editor Meghan Giannotta have your inside look at Newsday's summer FunBook. Credit: Newsday/Howard Schnapp, Kendall Rodriguez, Drew Singh; Anthony Florio, Randee Daddona, Morgan Campbell, Debbie Egan-Chin

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From celebrating America's 250th birthday to a new ride at Adventureland, NewsdayTV's Elisa DiStefano and Newsday lifestyle editor Meghan Giannotta have your inside look at Newsday's summer FunBook. Credit: Newsday/Howard Schnapp, Kendall Rodriguez, Drew Singh; Anthony Florio, Randee Daddona, Morgan Campbell, Debbie Egan-Chin

Get ready for sun and fun with NewsdayTV's summer FunBook special! From celebrating America's 250th birthday to a new ride at Adventureland, NewsdayTV's Elisa DiStefano and Newsday lifestyle editor Meghan Giannotta have your inside look at Newsday's summer FunBook.

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